WIP: use HdlOption[the_type_var] or UInt[123 + n] for creating types

.forgejo/workflows/test.yml

@@ -7,13 +7,14 @@ jobs:
       - uses: https://code.forgejo.org/actions/checkout@v3
         with:
           fetch-depth: 0
-      - run: |
-          curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --default-toolchain 1.79.0
-          source "$HOME/.cargo/env"
-          echo "$PATH" >> "$GITHUB_PATH"
-      - uses: https://github.com/Swatinem/rust-cache@v2
-        with:
-          save-if: ${{ github.ref == 'refs/heads/master' }}
-      - run: cargo test
-      - run: cargo test --features=unstable-doc
-      - run: cargo doc --features=unstable-doc
+# FIXME: uncomment once the code works again
+#      - run: |
+#          curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --default-toolchain 1.79.0
+#          source "$HOME/.cargo/env"
+#          echo "$PATH" >> "$GITHUB_PATH"
+#      - uses: https://github.com/Swatinem/rust-cache@v2
+#        with:
+#          save-if: ${{ github.ref == 'refs/heads/master' }}
+#      - run: cargo test
+#      - run: cargo test --features=unstable-doc
+#      - run: cargo doc --features=unstable-doc

crates/fayalite-proc-macros-impl/src/hdl_bundle.rs

@@ -0,0 +1,713 @@
+use crate::{
+    hdl_type_common::{common_derives, get_target, TypeOptions, WrappedInConst},
+    kw, Errors, HdlAttr, PairsIterExt,
+};
+use proc_macro2::TokenStream;
+use quote::{format_ident, quote_spanned, ToTokens};
+use syn::{
+    parse_quote, parse_quote_spanned,
+    punctuated::{Pair, Punctuated},
+    spanned::Spanned,
+    token::Brace,
+    AngleBracketedGenericArguments, Attribute, Field, FieldMutability, Fields, FieldsNamed,
+    GenericParam, Generics, Ident, ItemStruct, Path, Token, Type, Visibility,
+};
+
+#[derive(Clone, Debug)]
+pub(crate) struct ParsedBundle {
+    pub(crate) attrs: Vec<Attribute>,
+    pub(crate) options: HdlAttr<TypeOptions>,
+    pub(crate) vis: Visibility,
+    pub(crate) struct_token: Token![struct],
+    pub(crate) ident: Ident,
+    pub(crate) generics: Generics,
+    pub(crate) fields: FieldsNamed,
+    pub(crate) field_flips: Vec<Option<HdlAttr<kw::flip>>>,
+    pub(crate) mask_type_ident: Ident,
+    pub(crate) mask_type_match_variant_ident: Ident,
+    pub(crate) match_variant_ident: Ident,
+    pub(crate) builder_ident: Ident,
+    pub(crate) mask_type_builder_ident: Ident,
+}
+
+impl ParsedBundle {
+    fn parse_field(
+        errors: &mut Errors,
+        field: &mut Field,
+        index: usize,
+    ) -> Option<HdlAttr<kw::flip>> {
+        let Field {
+            attrs,
+            vis: _,
+            mutability,
+            ident,
+            colon_token,
+            ty,
+        } = field;
+        let ident = ident.get_or_insert_with(|| format_ident!("_{}", index, span = ty.span()));
+        if !matches!(mutability, FieldMutability::None) {
+            // FIXME: use mutability as the spanned tokens,
+            // blocked on https://github.com/dtolnay/syn/issues/1717
+            errors.error(&ident, "field mutability is not supported");
+            *mutability = FieldMutability::None;
+        }
+        *mutability = FieldMutability::None;
+        colon_token.get_or_insert(Token![:](ident.span()));
+        let options = errors.unwrap_or_default(HdlAttr::parse_and_take_attr(attrs));
+        options
+    }
+    fn parse(item: ItemStruct) -> syn::Result<Self> {
+        let ItemStruct {
+            mut attrs,
+            vis,
+            struct_token,
+            ident,
+            generics,
+            fields,
+            semi_token,
+        } = item;
+        let mut errors = Errors::new();
+        let options = errors
+            .unwrap_or_default(HdlAttr::parse_and_take_attr(&mut attrs))
+            .unwrap_or_default();
+        let mut fields = match fields {
+            syn::Fields::Named(fields) => fields,
+            syn::Fields::Unnamed(fields) => {
+                errors.error(&fields, "#[hdl] struct must use curly braces: {}");
+                FieldsNamed {
+                    brace_token: Brace(fields.paren_token.span),
+                    named: fields.unnamed,
+                }
+            }
+            syn::Fields::Unit => {
+                errors.error(&fields, "#[hdl] struct must use curly braces: {}");
+                FieldsNamed {
+                    brace_token: Brace(semi_token.unwrap_or_default().span),
+                    named: Punctuated::default(),
+                }
+            }
+        };
+        let mut field_flips = Vec::with_capacity(fields.named.len());
+        for (index, field) in fields.named.iter_mut().enumerate() {
+            field_flips.push(Self::parse_field(&mut errors, field, index));
+        }
+        errors.finish()?;
+        Ok(Self {
+            attrs,
+            options,
+            vis,
+            struct_token,
+            generics,
+            fields,
+            field_flips,
+            mask_type_ident: format_ident!("__{}__MaskType", ident),
+            mask_type_match_variant_ident: format_ident!("__{}__MaskType__MatchVariant", ident),
+            match_variant_ident: format_ident!("__{}__MatchVariant", ident),
+            mask_type_builder_ident: format_ident!("__{}__MaskType__Builder", ident),
+            builder_ident: format_ident!("__{}__Builder", ident),
+            ident,
+        })
+    }
+}
+
+#[derive(Clone, Debug)]
+struct Builder {
+    vis: Visibility,
+    struct_token: Token![struct],
+    ident: Ident,
+    target: Path,
+    generics: Generics,
+    fields: FieldsNamed,
+}
+
+#[derive(Copy, Clone, Eq, PartialEq, Debug)]
+enum BuilderFieldState {
+    Unfilled,
+    Generic,
+    Filled,
+}
+
+impl Builder {
+    fn phantom_field_name(&self) -> Ident {
+        format_ident!("__phantom", span = self.ident.span())
+    }
+    fn phantom_field(&self) -> Field {
+        let target = &self.target;
+        let type_generics = self.generics.split_for_impl().1;
+        Field {
+            attrs: vec![],
+            vis: Visibility::Inherited,
+            mutability: FieldMutability::None,
+            ident: Some(self.phantom_field_name()),
+            colon_token: Some(Token![:](self.ident.span())),
+            ty: parse_quote_spanned! {self.ident.span()=>
+                ::fayalite::__std::marker::PhantomData<#target #type_generics>
+            },
+        }
+    }
+    fn builder_struct_generics(
+        &self,
+        mut get_field_state: impl FnMut(usize) -> BuilderFieldState,
+    ) -> Generics {
+        let mut retval = self.generics.clone();
+        for (field_index, field) in self.fields.named.iter().enumerate() {
+            match get_field_state(field_index) {
+                BuilderFieldState::Unfilled | BuilderFieldState::Filled => continue,
+                BuilderFieldState::Generic => {}
+            }
+            if !retval.params.empty_or_trailing() {
+                retval.params.push_punct(Token![,](self.ident.span()));
+            }
+            retval.params.push_value(GenericParam::Type(
+                type_var_for_field_name(field.ident.as_ref().unwrap()).into(),
+            ));
+        }
+        retval
+    }
+    fn builder_struct_ty(
+        &self,
+        mut get_field_state: impl FnMut(usize) -> BuilderFieldState,
+    ) -> Type {
+        let mut ty_arguments: AngleBracketedGenericArguments = if self.generics.params.is_empty() {
+            parse_quote_spanned! {self.ident.span()=>
+                <>
+            }
+        } else {
+            let builder_type_generics = self.generics.split_for_impl().1;
+            parse_quote! { #builder_type_generics }
+        };
+        for (field_index, Field { ident, ty, .. }) in self.fields.named.iter().enumerate() {
+            let ident = ident.as_ref().unwrap();
+            if !ty_arguments.args.empty_or_trailing() {
+                ty_arguments.args.push_punct(Token![,](self.ident.span()));
+            }
+            ty_arguments
+                .args
+                .push_value(match get_field_state(field_index) {
+                    BuilderFieldState::Unfilled => parse_quote_spanned! {self.ident.span()=>
+                        ::fayalite::bundle::Unfilled<#ty>
+                    },
+                    BuilderFieldState::Generic => {
+                        let type_var = type_var_for_field_name(ident);
+                        parse_quote_spanned! {self.ident.span()=>
+                            #type_var
+                        }
+                    }
+                    BuilderFieldState::Filled => parse_quote_spanned! {self.ident.span()=>
+                        ::fayalite::expr::Expr<#ty>
+                    },
+                });
+        }
+        let ident = &self.ident;
+        parse_quote_spanned! {ident.span()=>
+            #ident #ty_arguments
+        }
+    }
+}
+
+fn type_var_for_field_name(ident: &Ident) -> Ident {
+    format_ident!("__T_{}", ident)
+}
+
+fn field_fn_for_field_name(ident: &Ident) -> Ident {
+    format_ident!("field_{}", ident)
+}
+
+impl ToTokens for Builder {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        let Self {
+            vis,
+            struct_token,
+            ident,
+            target,
+            generics,
+            fields,
+        } = self;
+        let phantom_field_name = self.phantom_field_name();
+        let builder_struct = ItemStruct {
+            attrs: vec![parse_quote_spanned! {ident.span()=>
+                #[allow(non_camel_case_types, dead_code)]
+            }],
+            vis: vis.clone(),
+            struct_token: *struct_token,
+            ident: ident.clone(),
+            generics: self.builder_struct_generics(|_| BuilderFieldState::Generic),
+            fields: Fields::Named(FieldsNamed {
+                brace_token: fields.brace_token,
+                named: Punctuated::from_iter(
+                    [Pair::Punctuated(
+                        self.phantom_field(),
+                        Token![,](self.ident.span()),
+                    )]
+                    .into_iter()
+                    .chain(fields.named.pairs().map_pair_value_ref(|field| {
+                        let ident = field.ident.as_ref().unwrap();
+                        let type_var = type_var_for_field_name(ident);
+                        Field {
+                            vis: Visibility::Inherited,
+                            ty: parse_quote_spanned! {ident.span()=>
+                                #type_var
+                            },
+                            ..field.clone()
+                        }
+                    })),
+                ),
+            }),
+            semi_token: None,
+        };
+        builder_struct.to_tokens(tokens);
+        let field_idents = Vec::from_iter(
+            self.fields
+                .named
+                .iter()
+                .map(|field| field.ident.as_ref().unwrap()),
+        );
+        for (
+            field_index,
+            Field {
+                vis,
+                ident: field_ident,
+                ty,
+                ..
+            },
+        ) in self.fields.named.iter().enumerate()
+        {
+            let field_ident = field_ident.as_ref().unwrap();
+            let fn_ident = field_fn_for_field_name(field_ident);
+            let fn_generics = self.builder_struct_generics(|i| {
+                if i == field_index {
+                    BuilderFieldState::Unfilled
+                } else {
+                    BuilderFieldState::Generic
+                }
+            });
+            let (impl_generics, _, where_clause) = fn_generics.split_for_impl();
+            let unfilled_ty = self.builder_struct_ty(|i| {
+                if i == field_index {
+                    BuilderFieldState::Unfilled
+                } else {
+                    BuilderFieldState::Generic
+                }
+            });
+            let filled_ty = self.builder_struct_ty(|i| {
+                if i == field_index {
+                    BuilderFieldState::Filled
+                } else {
+                    BuilderFieldState::Generic
+                }
+            });
+            let pat_fields =
+                Vec::from_iter(self.fields.named.iter().enumerate().map(|(i, field)| {
+                    let field_ident = field.ident.as_ref().unwrap();
+                    if field_index == i {
+                        quote_spanned! {self.ident.span()=>
+                            #field_ident: _,
+                        }
+                    } else {
+                        quote_spanned! {self.ident.span()=>
+                            #field_ident,
+                        }
+                    }
+                }));
+            quote_spanned! {self.ident.span()=>
+                #[automatically_derived]
+                #[allow(non_camel_case_types, dead_code)]
+                impl #impl_generics #unfilled_ty
+                #where_clause
+                {
+                    #vis fn #fn_ident(
+                        self,
+                        #field_ident: ::fayalite::expr::Expr<#ty>,
+                    ) -> #filled_ty {
+                        let Self {
+                            #phantom_field_name: _,
+                            #(#pat_fields)*
+                        } = self;
+                        #ident {
+                            #phantom_field_name: ::fayalite::__std::marker::PhantomData,
+                            #(#field_idents,)*
+                        }
+                    }
+                }
+            }
+            .to_tokens(tokens);
+        }
+        let unfilled_generics = self.builder_struct_generics(|_| BuilderFieldState::Unfilled);
+        let unfilled_ty = self.builder_struct_ty(|_| BuilderFieldState::Unfilled);
+        let (unfilled_impl_generics, _, unfilled_where_clause) = unfilled_generics.split_for_impl();
+        quote_spanned! {self.ident.span()=>
+            #[automatically_derived]
+            #[allow(non_camel_case_types, dead_code)]
+            impl #unfilled_impl_generics ::fayalite::__std::default::Default for #unfilled_ty
+            #unfilled_where_clause
+            {
+                fn default() -> Self {
+                    #ident {
+                        #phantom_field_name: ::fayalite::__std::marker::PhantomData,
+                        #(#field_idents: ::fayalite::__std::default::Default::default(),)*
+                    }
+                }
+            }
+        }
+        .to_tokens(tokens);
+        let filled_generics = self.builder_struct_generics(|_| BuilderFieldState::Filled);
+        let filled_ty = self.builder_struct_ty(|_| BuilderFieldState::Filled);
+        let (filled_impl_generics, _, filled_where_clause) = filled_generics.split_for_impl();
+        let type_generics = self.generics.split_for_impl().1;
+        quote_spanned! {self.ident.span()=>
+            #[automatically_derived]
+            #[allow(non_camel_case_types, dead_code)]
+            impl #filled_impl_generics ::fayalite::expr::ToExpr for #filled_ty
+            #filled_where_clause
+            {
+                type Type = #target #type_generics;
+                fn to_expr(
+                    &self,
+                ) -> ::fayalite::expr::Expr<<Self as ::fayalite::expr::ToExpr>::Type> {
+                    let __ty = #target {
+                        #(#field_idents: ::fayalite::expr::Expr::ty(self.#field_idents),)*
+                    };
+                    let __field_values = [
+                        #(::fayalite::expr::Expr::canonical(self.#field_idents),)*
+                    ];
+                    ::fayalite::expr::ToExpr::to_expr(
+                        &::fayalite::expr::ops::BundleLiteral::new(__ty, &__field_values),
+                    )
+                }
+            }
+        }
+        .to_tokens(tokens);
+    }
+}
+
+impl ToTokens for ParsedBundle {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        let Self {
+            attrs,
+            options,
+            vis,
+            struct_token,
+            ident,
+            generics,
+            fields,
+            field_flips,
+            mask_type_ident,
+            mask_type_match_variant_ident,
+            match_variant_ident,
+            builder_ident,
+            mask_type_builder_ident,
+        } = self;
+        let TypeOptions {
+            outline_generated: _,
+            connect_inexact,
+            target,
+        } = &options.body;
+        let target = get_target(target, ident);
+        let mut item_attrs = attrs.clone();
+        item_attrs.push(common_derives(ident.span()));
+        ItemStruct {
+            attrs: item_attrs,
+            vis: vis.clone(),
+            struct_token: *struct_token,
+            ident: ident.clone(),
+            generics: generics.clone(),
+            fields: Fields::Named(fields.clone()),
+            semi_token: None,
+        }
+        .to_tokens(tokens);
+        let (impl_generics, type_generics, where_clause) = generics.split_for_impl();
+        let mut wrapped_in_const = WrappedInConst::new(tokens, ident.span());
+        let tokens = wrapped_in_const.inner();
+        let builder = Builder {
+            vis: vis.clone(),
+            struct_token: *struct_token,
+            ident: builder_ident.clone(),
+            target: target.clone(),
+            generics: generics.clone(),
+            fields: fields.clone(),
+        };
+        builder.to_tokens(tokens);
+        let unfilled_builder_ty = builder.builder_struct_ty(|_| BuilderFieldState::Unfilled);
+        let filled_builder_ty = builder.builder_struct_ty(|_| BuilderFieldState::Filled);
+        let mut mask_type_fields = fields.clone();
+        for Field { ident, ty, .. } in &mut mask_type_fields.named {
+            let ident = ident.as_ref().unwrap();
+            *ty = parse_quote_spanned! {ident.span()=>
+                <#ty as ::fayalite::ty::Type>::MaskType
+            };
+        }
+        let mask_type_builder = Builder {
+            vis: vis.clone(),
+            struct_token: *struct_token,
+            ident: mask_type_builder_ident.clone(),
+            target: mask_type_ident.clone().into(),
+            generics: generics.clone(),
+            fields: mask_type_fields.clone(),
+        };
+        mask_type_builder.to_tokens(tokens);
+        let unfilled_mask_type_builder_ty =
+            mask_type_builder.builder_struct_ty(|_| BuilderFieldState::Unfilled);
+        let filled_mask_type_builder_ty =
+            mask_type_builder.builder_struct_ty(|_| BuilderFieldState::Filled);
+        ItemStruct {
+            attrs: vec![
+                common_derives(ident.span()),
+                parse_quote_spanned! {ident.span()=>
+                    #[allow(non_camel_case_types, dead_code)]
+                },
+            ],
+            vis: vis.clone(),
+            struct_token: *struct_token,
+            ident: mask_type_ident.clone(),
+            generics: generics.clone(),
+            fields: Fields::Named(mask_type_fields.clone()),
+            semi_token: None,
+        }
+        .to_tokens(tokens);
+        let mut mask_type_match_variant_fields = mask_type_fields;
+        for Field { ident, ty, .. } in &mut mask_type_match_variant_fields.named {
+            let ident = ident.as_ref().unwrap();
+            *ty = parse_quote_spanned! {ident.span()=>
+                ::fayalite::expr::Expr<#ty>
+            };
+        }
+        ItemStruct {
+            attrs: vec![
+                common_derives(ident.span()),
+                parse_quote_spanned! {ident.span()=>
+                    #[allow(non_camel_case_types, dead_code)]
+                },
+            ],
+            vis: vis.clone(),
+            struct_token: *struct_token,
+            ident: mask_type_match_variant_ident.clone(),
+            generics: generics.clone(),
+            fields: Fields::Named(mask_type_match_variant_fields),
+            semi_token: None,
+        }
+        .to_tokens(tokens);
+        let mut match_variant_fields = fields.clone();
+        for Field { ident, ty, .. } in &mut match_variant_fields.named {
+            let ident = ident.as_ref().unwrap();
+            *ty = parse_quote_spanned! {ident.span()=>
+                ::fayalite::expr::Expr<#ty>
+            };
+        }
+        ItemStruct {
+            attrs: vec![
+                common_derives(ident.span()),
+                parse_quote_spanned! {ident.span()=>
+                    #[allow(non_camel_case_types, dead_code)]
+                },
+            ],
+            vis: vis.clone(),
+            struct_token: *struct_token,
+            ident: match_variant_ident.clone(),
+            generics: generics.clone(),
+            fields: Fields::Named(match_variant_fields),
+            semi_token: None,
+        }
+        .to_tokens(tokens);
+        let match_variant_body_fields =
+            Vec::from_iter(fields.named.iter().map(|Field { ident, .. }| {
+                let ident: &Ident = ident.as_ref().unwrap();
+                let ident_str = ident.to_string();
+                quote_spanned! {ident.span()=>
+                    #ident: ::fayalite::expr::Expr::field(__this, #ident_str),
+                }
+            }));
+        let mask_type_body_fields =
+            Vec::from_iter(fields.named.iter().map(|Field { ident, .. }| {
+                let ident: &Ident = ident.as_ref().unwrap();
+                quote_spanned! {ident.span()=>
+                    #ident: ::fayalite::ty::Type::mask_type(&self.#ident),
+                }
+            }));
+        let from_canonical_body_fields =
+            Vec::from_iter(fields.named.iter().enumerate().zip(field_flips).map(
+                |((index, Field { ident, .. }), flip)| {
+                    let ident: &Ident = ident.as_ref().unwrap();
+                    let ident_str = ident.to_string();
+                    let flipped = flip.is_some();
+                    quote_spanned! {ident.span()=>
+                        #ident: {
+                            let ::fayalite::bundle::BundleField {
+                                name: __name,
+                                flipped: __flipped,
+                                ty: __ty,
+                            } = __fields[#index];
+                            ::fayalite::__std::assert_eq!(&*__name, #ident_str);
+                            ::fayalite::__std::assert_eq!(__flipped, #flipped);
+                            ::fayalite::ty::Type::from_canonical(__ty)
+                        },
+                    }
+                },
+            ));
+        let fields_body_fields = Vec::from_iter(fields.named.iter().zip(field_flips).map(
+            |(Field { ident, .. }, flip)| {
+                let ident: &Ident = ident.as_ref().unwrap();
+                let ident_str = ident.to_string();
+                let flipped = flip.is_some();
+                quote_spanned! {ident.span()=>
+                    ::fayalite::bundle::BundleField {
+                        name: ::fayalite::intern::Intern::intern(#ident_str),
+                        flipped: #flipped,
+                        ty: ::fayalite::ty::Type::canonical(&self.#ident),
+                    },
+                }
+            },
+        ));
+        let fields_len = fields.named.len();
+        quote_spanned! {ident.span()=>
+            #[automatically_derived]
+            impl #impl_generics ::fayalite::ty::Type for #mask_type_ident #type_generics
+            #where_clause
+            {
+                type MaskType = #mask_type_ident #type_generics;
+                type MatchVariant = #mask_type_match_variant_ident #type_generics;
+                type MatchActiveScope = ();
+                type MatchVariantAndInactiveScope = ::fayalite::ty::MatchVariantWithoutScope<
+                    <Self as ::fayalite::ty::Type>::MatchVariant,
+                >;
+                type MatchVariantsIter = ::fayalite::__std::iter::Once<
+                    <Self as ::fayalite::ty::Type>::MatchVariantAndInactiveScope,
+                >;
+                fn match_variants(
+                    __this: ::fayalite::expr::Expr<Self>,
+                    __module_builder: &mut ::fayalite::module::ModuleBuilder<
+                        ::fayalite::module::NormalModule,
+                    >,
+                    __source_location: ::fayalite::source_location::SourceLocation,
+                ) -> <Self as ::fayalite::ty::Type>::MatchVariantsIter {
+                    let __retval = #mask_type_match_variant_ident {
+                        #(#match_variant_body_fields)*
+                    };
+                    ::fayalite::__std::iter::once(::fayalite::ty::MatchVariantWithoutScope(__retval))
+                }
+                fn mask_type(&self) -> <Self as ::fayalite::ty::Type>::MaskType {
+                    *self
+                }
+                fn canonical(&self) -> ::fayalite::ty::CanonicalType {
+                    ::fayalite::ty::Type::canonical(&::fayalite::bundle::Bundle::new(::fayalite::bundle::BundleType::fields(self)))
+                }
+                #[track_caller]
+                fn from_canonical(__canonical_type: ::fayalite::ty::CanonicalType) -> Self {
+                    let ::fayalite::ty::CanonicalType::Bundle(__bundle) = __canonical_type else {
+                        ::fayalite::__std::panic!("expected bundle");
+                    };
+                    let __fields = ::fayalite::bundle::BundleType::fields(&__bundle);
+                    ::fayalite::__std::assert_eq!(__fields.len(), #fields_len, "bundle has wrong number of fields");
+                    Self {
+                        #(#from_canonical_body_fields)*
+                    }
+                }
+                fn source_location() -> ::fayalite::source_location::SourceLocation {
+                    ::fayalite::source_location::SourceLocation::caller()
+                }
+            }
+            #[automatically_derived]
+            impl #impl_generics ::fayalite::bundle::BundleType for #mask_type_ident #type_generics
+            #where_clause
+            {
+                type Builder = #unfilled_mask_type_builder_ty;
+                type FilledBuilder = #filled_mask_type_builder_ty;
+                fn fields(&self) -> ::fayalite::intern::Interned<[::fayalite::bundle::BundleField]> {
+                    ::fayalite::intern::Intern::intern(&[#(#fields_body_fields)*][..])
+                }
+            }
+            #[automatically_derived]
+            impl #impl_generics ::fayalite::ty::TypeWithDeref for #mask_type_ident #type_generics
+            #where_clause
+            {
+                fn expr_deref(__this: &::fayalite::expr::Expr<Self>) -> &<Self as ::fayalite::ty::Type>::MatchVariant {
+                    let __this = *__this;
+                    let __retval = #mask_type_match_variant_ident {
+                        #(#match_variant_body_fields)*
+                    };
+                    ::fayalite::intern::Interned::<_>::into_inner(::fayalite::intern::Intern::intern_sized(__retval))
+                }
+            }
+            #[automatically_derived]
+            impl #impl_generics ::fayalite::ty::Type for #target #type_generics
+            #where_clause
+            {
+                type MaskType = #mask_type_ident #type_generics;
+                type MatchVariant = #match_variant_ident #type_generics;
+                type MatchActiveScope = ();
+                type MatchVariantAndInactiveScope = ::fayalite::ty::MatchVariantWithoutScope<
+                    <Self as ::fayalite::ty::Type>::MatchVariant,
+                >;
+                type MatchVariantsIter = ::fayalite::__std::iter::Once<
+                    <Self as ::fayalite::ty::Type>::MatchVariantAndInactiveScope,
+                >;
+                fn match_variants(
+                    __this: ::fayalite::expr::Expr<Self>,
+                    __module_builder: &mut ::fayalite::module::ModuleBuilder<
+                        ::fayalite::module::NormalModule,
+                    >,
+                    __source_location: ::fayalite::source_location::SourceLocation,
+                ) -> <Self as ::fayalite::ty::Type>::MatchVariantsIter {
+                    let __retval = #match_variant_ident {
+                        #(#match_variant_body_fields)*
+                    };
+                    ::fayalite::__std::iter::once(::fayalite::ty::MatchVariantWithoutScope(__retval))
+                }
+                fn mask_type(&self) -> <Self as ::fayalite::ty::Type>::MaskType {
+                    #mask_type_ident {
+                        #(#mask_type_body_fields)*
+                    }
+                }
+                fn canonical(&self) -> ::fayalite::ty::CanonicalType {
+                    ::fayalite::ty::Type::canonical(&::fayalite::bundle::Bundle::new(::fayalite::bundle::BundleType::fields(self)))
+                }
+                #[track_caller]
+                fn from_canonical(__canonical_type: ::fayalite::ty::CanonicalType) -> Self {
+                    let ::fayalite::ty::CanonicalType::Bundle(__bundle) = __canonical_type else {
+                        ::fayalite::__std::panic!("expected bundle");
+                    };
+                    let __fields = ::fayalite::bundle::BundleType::fields(&__bundle);
+                    ::fayalite::__std::assert_eq!(__fields.len(), #fields_len, "bundle has wrong number of fields");
+                    Self {
+                        #(#from_canonical_body_fields)*
+                    }
+                }
+                fn source_location() -> ::fayalite::source_location::SourceLocation {
+                    ::fayalite::source_location::SourceLocation::caller()
+                }
+            }
+            #[automatically_derived]
+            impl #impl_generics ::fayalite::bundle::BundleType for #target #type_generics
+            #where_clause
+            {
+                type Builder = #unfilled_builder_ty;
+                type FilledBuilder = #filled_builder_ty;
+                fn fields(&self) -> ::fayalite::intern::Interned<[::fayalite::bundle::BundleField]> {
+                    ::fayalite::intern::Intern::intern(&[#(#fields_body_fields)*][..])
+                }
+            }
+            #[automatically_derived]
+            impl #impl_generics ::fayalite::ty::TypeWithDeref for #target #type_generics
+            #where_clause
+            {
+                fn expr_deref(__this: &::fayalite::expr::Expr<Self>) -> &<Self as ::fayalite::ty::Type>::MatchVariant {
+                    let __this = *__this;
+                    let __retval = #match_variant_ident {
+                        #(#match_variant_body_fields)*
+                    };
+                    ::fayalite::intern::Interned::<_>::into_inner(::fayalite::intern::Intern::intern_sized(__retval))
+                }
+            }
+        }
+        .to_tokens(tokens);
+    }
+}
+
+pub(crate) fn hdl_bundle(item: ItemStruct) -> syn::Result<TokenStream> {
+    let item = ParsedBundle::parse(item)?;
+    let outline_generated = item.options.body.outline_generated;
+    let mut contents = item.to_token_stream();
+    if outline_generated.is_some() {
+        contents = crate::outline_generated(contents, "hdl-bundle-");
+    }
+    Ok(contents)
+}

crates/fayalite-proc-macros-impl/src/hdl_enum.rs

@@ -0,0 +1,551 @@
+use crate::{
+    hdl_type_common::{common_derives, get_target, TypeOptions, WrappedInConst},
+    Errors, HdlAttr, PairsIterExt,
+};
+use proc_macro2::TokenStream;
+use quote::{format_ident, quote_spanned, ToTokens};
+use syn::{
+    parse_quote_spanned,
+    punctuated::{Pair, Punctuated},
+    token::{Brace, Paren},
+    Attribute, Field, FieldMutability, Fields, FieldsNamed, FieldsUnnamed, Generics, Ident,
+    ItemEnum, ItemStruct, Token, Type, Variant, Visibility,
+};
+
+crate::options! {
+    #[options = VariantOptions]
+    pub(crate) enum VariantOption {}
+}
+
+crate::options! {
+    #[options = FieldOptions]
+    pub(crate) enum FieldOption {}
+}
+
+#[derive(Clone, Debug)]
+pub(crate) struct ParsedField {
+    pub(crate) paren_token: Paren,
+    pub(crate) attrs: Vec<Attribute>,
+    pub(crate) options: HdlAttr<FieldOptions>,
+    pub(crate) ty: Type,
+    pub(crate) comma_token: Option<Token![,]>,
+}
+
+#[derive(Clone, Debug)]
+pub(crate) struct ParsedVariant {
+    pub(crate) attrs: Vec<Attribute>,
+    pub(crate) options: HdlAttr<VariantOptions>,
+    pub(crate) ident: Ident,
+    pub(crate) field: Option<ParsedField>,
+}
+
+impl ParsedVariant {
+    fn parse(errors: &mut Errors, variant: Variant) -> Self {
+        let Variant {
+            mut attrs,
+            ident,
+            fields,
+            discriminant,
+        } = variant;
+        let options = errors
+            .unwrap_or_default(HdlAttr::parse_and_take_attr(&mut attrs))
+            .unwrap_or_default();
+        let field = match fields {
+            Fields::Unnamed(FieldsUnnamed {
+                paren_token,
+                unnamed,
+            }) if unnamed.len() == 1 => {
+                let (field, comma_token) = unnamed.into_pairs().next().unwrap().into_tuple();
+                let Field {
+                    mut attrs,
+                    vis,
+                    mutability,
+                    ident: _,
+                    colon_token: _,
+                    ty,
+                } = field;
+                let options = errors
+                    .unwrap_or_default(HdlAttr::parse_and_take_attr(&mut attrs))
+                    .unwrap_or_default();
+                if !matches!(vis, Visibility::Inherited) {
+                    // FIXME: use mutability as the spanned tokens,
+                    // blocked on https://github.com/dtolnay/syn/issues/1717
+                    errors.error(
+                        &vis,
+                        "enum variant fields must not have a visibility specifier",
+                    );
+                }
+                if !matches!(mutability, FieldMutability::None) {
+                    // FIXME: use mutability as the spanned tokens,
+                    // blocked on https://github.com/dtolnay/syn/issues/1717
+                    errors.error(&ty, "field mutability is not supported");
+                }
+                Some(ParsedField {
+                    paren_token,
+                    attrs,
+                    options,
+                    ty,
+                    comma_token,
+                })
+            }
+            Fields::Unit => None,
+            Fields::Unnamed(fields) if fields.unnamed.is_empty() => None,
+            Fields::Named(fields) if fields.named.is_empty() => None,
+            Fields::Unnamed(_) | Fields::Named(_) => {
+                errors.error(
+                    fields,
+                    "enum variant must either have no fields or a single parenthesized field",
+                );
+                None
+            }
+        };
+        if let Some((eq, _)) = discriminant {
+            errors.error(eq, "custom enum discriminants are not allowed");
+        }
+        Self {
+            attrs,
+            options,
+            ident,
+            field,
+        }
+    }
+}
+
+#[derive(Clone, Debug)]
+pub(crate) struct ParsedEnum {
+    pub(crate) attrs: Vec<Attribute>,
+    pub(crate) options: HdlAttr<TypeOptions>,
+    pub(crate) vis: Visibility,
+    pub(crate) enum_token: Token![enum],
+    pub(crate) ident: Ident,
+    pub(crate) generics: Generics,
+    pub(crate) brace_token: Brace,
+    pub(crate) variants: Punctuated<ParsedVariant, Token![,]>,
+    pub(crate) match_variant_ident: Ident,
+}
+
+impl ParsedEnum {
+    fn parse(item: ItemEnum) -> syn::Result<Self> {
+        let ItemEnum {
+            mut attrs,
+            vis,
+            enum_token,
+            ident,
+            generics,
+            brace_token,
+            variants,
+        } = item;
+        let mut errors = Errors::new();
+        let options = errors
+            .unwrap_or_default(HdlAttr::parse_and_take_attr(&mut attrs))
+            .unwrap_or_default();
+        attrs.retain(|attr| {
+            if attr.path().is_ident("repr") {
+                errors.error(attr, "#[repr] is not supported on #[hdl] enums");
+                false
+            } else {
+                true
+            }
+        });
+        let variants = Punctuated::from_iter(
+            variants
+                .into_pairs()
+                .map_pair_value(|v| ParsedVariant::parse(&mut errors, v)),
+        );
+        errors.finish()?;
+        Ok(Self {
+            attrs,
+            options,
+            vis,
+            enum_token,
+            generics,
+            brace_token,
+            variants,
+            match_variant_ident: format_ident!("__{}__MatchVariant", ident),
+            ident,
+        })
+    }
+}
+
+impl ToTokens for ParsedEnum {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        let Self {
+            attrs,
+            options,
+            vis,
+            enum_token,
+            ident,
+            generics,
+            brace_token,
+            variants,
+            match_variant_ident,
+        } = self;
+        let TypeOptions {
+            outline_generated: _,
+            connect_inexact,
+            target,
+        } = &options.body;
+        let target = get_target(target, ident);
+        let mut struct_attrs = attrs.clone();
+        struct_attrs.push(common_derives(ident.span()));
+        struct_attrs.push(parse_quote_spanned! {ident.span()=>
+            #[allow(non_snake_case)]
+        });
+        let struct_fields = Punctuated::from_iter(variants.pairs().map_pair_value_ref(
+            |ParsedVariant {
+                 attrs: _,
+                 options,
+                 ident,
+                 field,
+             }| {
+                let VariantOptions {} = options.body;
+                let colon_token;
+                let ty = if let Some(ParsedField {
+                    paren_token,
+                    attrs: _,
+                    options,
+                    ty,
+                    comma_token: _,
+                }) = field
+                {
+                    let FieldOptions {} = options.body;
+                    colon_token = Token![:](paren_token.span.open());
+                    ty.clone()
+                } else {
+                    colon_token = Token![:](ident.span());
+                    parse_quote_spanned! {ident.span()=>
+                        ()
+                    }
+                };
+                Field {
+                    attrs: vec![],
+                    vis: vis.clone(),
+                    mutability: FieldMutability::None,
+                    ident: Some(ident.clone()),
+                    colon_token: Some(colon_token),
+                    ty,
+                }
+            },
+        ));
+        ItemStruct {
+            attrs: struct_attrs,
+            vis: vis.clone(),
+            struct_token: Token![struct](enum_token.span),
+            ident: ident.clone(),
+            generics: generics.clone(),
+            fields: if struct_fields.is_empty() {
+                Fields::Unit
+            } else {
+                Fields::Named(FieldsNamed {
+                    brace_token: *brace_token,
+                    named: struct_fields,
+                })
+            },
+            semi_token: None,
+        }
+        .to_tokens(tokens);
+        let (impl_generics, type_generics, where_clause) = generics.split_for_impl();
+        let mut wrapped_in_const = WrappedInConst::new(tokens, ident.span());
+        let tokens = wrapped_in_const.inner();
+        {
+            let mut wrapped_in_const = WrappedInConst::new(tokens, ident.span());
+            let tokens = wrapped_in_const.inner();
+            let mut enum_attrs = attrs.clone();
+            enum_attrs.push(parse_quote_spanned! {ident.span()=>
+                #[allow(dead_code)]
+            });
+            ItemEnum {
+                attrs: enum_attrs,
+                vis: vis.clone(),
+                enum_token: *enum_token,
+                ident: ident.clone(),
+                generics: generics.clone(),
+                brace_token: *brace_token,
+                variants: Punctuated::from_iter(variants.pairs().map_pair_value_ref(
+                    |ParsedVariant {
+                         attrs,
+                         options: _,
+                         ident,
+                         field,
+                     }| Variant {
+                        attrs: attrs.clone(),
+                        ident: ident.clone(),
+                        fields: match field {
+                            Some(ParsedField {
+                                paren_token,
+                                attrs,
+                                options: _,
+                                ty,
+                                comma_token,
+                            }) => Fields::Unnamed(FieldsUnnamed {
+                                paren_token: *paren_token,
+                                unnamed: Punctuated::from_iter([Pair::new(
+                                    Field {
+                                        attrs: attrs.clone(),
+                                        vis: Visibility::Inherited,
+                                        mutability: FieldMutability::None,
+                                        ident: None,
+                                        colon_token: None,
+                                        ty: ty.clone(),
+                                    },
+                                    *comma_token,
+                                )]),
+                            }),
+                            None => Fields::Unit,
+                        },
+                        discriminant: None,
+                    },
+                )),
+            }
+            .to_tokens(tokens);
+        }
+        let mut enum_attrs = attrs.clone();
+        enum_attrs.push(parse_quote_spanned! {ident.span()=>
+            #[allow(dead_code, non_camel_case_types)]
+        });
+        ItemEnum {
+            attrs: enum_attrs,
+            vis: vis.clone(),
+            enum_token: *enum_token,
+            ident: match_variant_ident.clone(),
+            generics: generics.clone(),
+            brace_token: *brace_token,
+            variants: Punctuated::from_iter(variants.pairs().map_pair_value_ref(
+                |ParsedVariant {
+                     attrs,
+                     options: _,
+                     ident,
+                     field,
+                 }| Variant {
+                    attrs: attrs.clone(),
+                    ident: ident.clone(),
+                    fields: match field {
+                        Some(ParsedField {
+                            paren_token,
+                            attrs,
+                            options: _,
+                            ty,
+                            comma_token,
+                        }) => Fields::Unnamed(FieldsUnnamed {
+                            paren_token: *paren_token,
+                            unnamed: Punctuated::from_iter([Pair::new(
+                                Field {
+                                    attrs: attrs.clone(),
+                                    vis: Visibility::Inherited,
+                                    mutability: FieldMutability::None,
+                                    ident: None,
+                                    colon_token: None,
+                                    ty: parse_quote_spanned! {ident.span()=>
+                                        ::fayalite::expr::Expr<#ty>
+                                    },
+                                },
+                                *comma_token,
+                            )]),
+                        }),
+                        None => Fields::Unit,
+                    },
+                    discriminant: None,
+                },
+            )),
+        }
+        .to_tokens(tokens);
+        for (index, ParsedVariant { ident, field, .. }) in variants.iter().enumerate() {
+            if let Some(ParsedField { ty, .. }) = field {
+                quote_spanned! {ident.span()=>
+                    #[automatically_derived]
+                    impl #impl_generics #target #type_generics
+                    #where_clause
+                    {
+                        #[allow(non_snake_case, dead_code)]
+                        #vis fn #ident<__V: ::fayalite::expr::ToExpr<Type = #ty>>(
+                            self,
+                            v: __V,
+                        ) -> ::fayalite::expr::Expr<Self> {
+                            ::fayalite::expr::ToExpr::to_expr(
+                                &::fayalite::expr::ops::EnumLiteral::new(
+                                    self,
+                                    #index,
+                                    ::fayalite::__std::option::Option::Some(
+                                        ::fayalite::expr::Expr::canonical(
+                                            ::fayalite::expr::ToExpr::to_expr(&v),
+                                        ),
+                                    ),
+                                ),
+                            )
+                        }
+                    }
+                }
+            } else {
+                quote_spanned! {ident.span()=>
+                    #[automatically_derived]
+                    impl #impl_generics #target #type_generics
+                    #where_clause
+                    {
+                        #[allow(non_snake_case, dead_code)]
+                        #vis fn #ident(self) -> ::fayalite::expr::Expr<Self> {
+                            ::fayalite::expr::ToExpr::to_expr(
+                                &::fayalite::expr::ops::EnumLiteral::new(
+                                    self,
+                                    #index,
+                                    ::fayalite::__std::option::Option::None,
+                                ),
+                            )
+                        }
+                    }
+                }
+            }
+            .to_tokens(tokens);
+        }
+        let from_canonical_body_fields = Vec::from_iter(variants.iter().enumerate().map(
+            |(index, ParsedVariant { ident, field, .. })| {
+                let ident_str = ident.to_string();
+                let var = format_ident!("_variant_{}", ident);
+                let val = if field.is_some() {
+                    let missing_value_msg = format!("expected variant {ident} to have a field");
+                    quote_spanned! {ident.span()=>
+                        ::fayalite::ty::Type::from_canonical(ty.expect(#missing_value_msg))
+                    }
+                } else {
+                    quote_spanned! {ident.span()=>
+                        ::fayalite::__std::assert!(ty.is_none());
+                    }
+                };
+                quote_spanned! {ident.span()=>
+                    #ident: {
+                        let ::fayalite::enum_::EnumVariant {
+                            name,
+                            ty,
+                        } = variants[#index];
+                        ::fayalite::__std::assert_eq!(&*name, #ident_str);
+                        #val
+                    },
+                }
+            },
+        ));
+        let match_active_scope_match_arms = Vec::from_iter(variants.iter().enumerate().map(
+            |(index, ParsedVariant { ident, field, .. })| {
+                if field.is_some() {
+                    quote_spanned! {ident.span()=>
+                        #index => #match_variant_ident::#ident(
+                            ::fayalite::expr::ToExpr::to_expr(
+                                &::fayalite::expr::ops::VariantAccess::new_unchecked(
+                                    variant_access.base(),
+                                    variant_access.variant_index(),
+                                ),
+                            ),
+                        ),
+                    }
+                } else {
+                    quote_spanned! {ident.span()=>
+                        #index => #match_variant_ident::#ident,
+                    }
+                }
+            },
+        ));
+        let variants_body_variants = Vec::from_iter(variants.iter().map(
+            |ParsedVariant {
+                 attrs: _,
+                 options,
+                 ident,
+                 field,
+             }| {
+                let VariantOptions {} = options.body;
+                let ident_str = ident.to_string();
+                match field {
+                    Some(ParsedField { options, .. }) => {
+                        let FieldOptions {} = options.body;
+                        quote_spanned! {ident.span()=>
+                            ::fayalite::enum_::EnumVariant {
+                                name: ::fayalite::intern::Intern::intern(#ident_str),
+                                ty: ::fayalite::__std::option::Option::Some(
+                                    ::fayalite::ty::Type::canonical(&self.#ident),
+                                ),
+                            },
+                        }
+                    }
+                    None => quote_spanned! {ident.span()=>
+                        ::fayalite::enum_::EnumVariant {
+                            name: ::fayalite::intern::Intern::intern(#ident_str),
+                            ty: ::fayalite::__std::option::Option::None,
+                        },
+                    },
+                }
+            },
+        ));
+        let variants_len = variants.len();
+        quote_spanned! {ident.span()=>
+            #[automatically_derived]
+            impl #impl_generics ::fayalite::ty::Type for #target #type_generics
+            #where_clause
+            {
+                type MaskType = ::fayalite::int::Bool;
+                type MatchVariant = #match_variant_ident #type_generics;
+                type MatchActiveScope = ::fayalite::module::Scope;
+                type MatchVariantAndInactiveScope = ::fayalite::enum_::EnumMatchVariantAndInactiveScope<Self>;
+                type MatchVariantsIter = ::fayalite::enum_::EnumMatchVariantsIter<Self>;
+
+                fn match_variants(
+                    this: ::fayalite::expr::Expr<Self>,
+                    module_builder: &mut ::fayalite::module::ModuleBuilder<::fayalite::module::NormalModule>,
+                    source_location: ::fayalite::source_location::SourceLocation,
+                ) -> <Self as ::fayalite::ty::Type>::MatchVariantsIter {
+                    module_builder.enum_match_variants_helper(this, source_location)
+                }
+                fn mask_type(&self) -> <Self as ::fayalite::ty::Type>::MaskType {
+                    ::fayalite::int::Bool
+                }
+                fn canonical(&self) -> ::fayalite::ty::CanonicalType {
+                    ::fayalite::ty::CanonicalType::Enum(::fayalite::enum_::Enum::new(::fayalite::enum_::EnumType::variants(self)))
+                }
+                #[track_caller]
+                #[allow(non_snake_case)]
+                fn from_canonical(canonical_type: ::fayalite::ty::CanonicalType) -> Self {
+                    let ::fayalite::ty::CanonicalType::Enum(enum_) = canonical_type else {
+                        ::fayalite::__std::panic!("expected enum");
+                    };
+                    let variants = ::fayalite::enum_::EnumType::variants(&enum_);
+                    ::fayalite::__std::assert_eq!(variants.len(), #variants_len, "enum has wrong number of variants");
+                    Self {
+                        #(#from_canonical_body_fields)*
+                    }
+                }
+                fn source_location() -> ::fayalite::source_location::SourceLocation {
+                    ::fayalite::source_location::SourceLocation::caller()
+                }
+            }
+            #[automatically_derived]
+            impl #impl_generics ::fayalite::enum_::EnumType for #target #type_generics
+            #where_clause
+            {
+                fn match_activate_scope(
+                    v: <Self as ::fayalite::ty::Type>::MatchVariantAndInactiveScope,
+                ) -> (<Self as ::fayalite::ty::Type>::MatchVariant, <Self as ::fayalite::ty::Type>::MatchActiveScope) {
+                    let (variant_access, scope) = v.activate();
+                    (
+                        match variant_access.variant_index() {
+                            #(#match_active_scope_match_arms)*
+                            #variants_len.. => ::fayalite::__std::panic!("invalid variant index"),
+                        },
+                        scope,
+                    )
+                }
+                fn variants(&self) -> ::fayalite::intern::Interned<[::fayalite::enum_::EnumVariant]> {
+                    ::fayalite::intern::Intern::intern(&[
+                        #(#variants_body_variants)*
+                    ][..])
+                }
+            }
+        }
+        .to_tokens(tokens);
+    }
+}
+
+pub(crate) fn hdl_enum(item: ItemEnum) -> syn::Result<TokenStream> {
+    let item = ParsedEnum::parse(item)?;
+    let outline_generated = item.options.body.outline_generated;
+    let mut contents = item.to_token_stream();
+    if outline_generated.is_some() {
+        contents = crate::outline_generated(contents, "hdl-enum-");
+    }
+    Ok(contents)
+}

crates/fayalite-proc-macros-impl/src/hdl_type_common.rs

@@ -0,0 +1,415 @@
+use crate::{fold::impl_fold, kw, Errors, HdlAttr, PairsIterExt};
+use proc_macro2::{Span, TokenStream};
+use quote::{quote, quote_spanned, ToTokens};
+use std::fmt;
+use syn::{
+    parse::{Parse, ParseStream},
+    parse_quote, parse_quote_spanned,
+    punctuated::Punctuated,
+    token::Paren,
+    Attribute, ConstParam, GenericParam, Generics, Ident, ImplGenerics, LifetimeParam, Path,
+    PredicateType, Token, Turbofish, Type, TypeGenerics, TypeParam, WhereClause, WherePredicate,
+};
+
+crate::options! {
+    #[options = TypeOptions]
+    pub(crate) enum TypeOption {
+        OutlineGenerated(outline_generated),
+        ConnectInexact(connect_inexact),
+        Target(target, Path),
+    }
+}
+
+pub(crate) struct WrappedInConst<'a> {
+    outer: &'a mut TokenStream,
+    span: Span,
+    inner: TokenStream,
+}
+
+impl<'a> WrappedInConst<'a> {
+    pub(crate) fn new(outer: &'a mut TokenStream, span: Span) -> Self {
+        Self {
+            outer,
+            span,
+            inner: TokenStream::new(),
+        }
+    }
+    pub(crate) fn inner(&mut self) -> &mut TokenStream {
+        &mut self.inner
+    }
+}
+
+impl Drop for WrappedInConst<'_> {
+    fn drop(&mut self) {
+        let inner = &self.inner;
+        quote_spanned! {self.span=>
+            const _: () = {
+                #inner
+            };
+        }
+        .to_tokens(self.outer);
+    }
+}
+
+pub(crate) fn get_target(target: &Option<(kw::target, Paren, Path)>, item_ident: &Ident) -> Path {
+    match target {
+        Some((_, _, target)) => target.clone(),
+        None => item_ident.clone().into(),
+    }
+}
+
+pub(crate) fn common_derives(span: Span) -> Attribute {
+    parse_quote_spanned! {span=>
+        #[::fayalite::__std::prelude::v1::derive(
+            ::fayalite::__std::fmt::Debug,
+            ::fayalite::__std::cmp::Eq,
+            ::fayalite::__std::cmp::PartialEq,
+            ::fayalite::__std::hash::Hash,
+            ::fayalite::__std::marker::Copy,
+            ::fayalite::__std::clone::Clone,
+        )]
+    }
+}
+
+crate::options! {
+    #[options = LifetimeParamOptions]
+    enum LifetimeParamOption {}
+}
+
+crate::options! {
+    #[options = TypeParamOptions]
+    pub(crate) enum TypeParamOption {}
+}
+
+crate::options! {
+    #[options = ConstParamOptions]
+    pub(crate) enum ConstParamOption {}
+}
+
+#[derive(Debug, Clone)]
+pub(crate) enum ParsedType {}
+
+impl ParsedType {
+    pub(crate) fn parse(ty: &mut Type) -> syn::Result<Self> {
+        todo!()
+    }
+}
+
+#[derive(Debug, Clone)]
+pub(crate) struct ParsedTypeParam {
+    pub(crate) attrs: Vec<Attribute>,
+    pub(crate) options: HdlAttr<TypeParamOptions>,
+    pub(crate) ident: Ident,
+    pub(crate) default: Option<(Token![=], ParsedType)>,
+}
+
+#[derive(Debug, Clone)]
+pub(crate) enum ParsedGenericParam {
+    Type(ParsedTypeParam),
+}
+
+#[derive(Debug, Clone)]
+pub(crate) struct ParsedGenerics {
+    pub(crate) lt_token: Option<Token![<]>,
+    pub(crate) params: Punctuated<ParsedGenericParam, Token![,]>,
+    pub(crate) gt_token: Option<Token![>]>,
+}
+
+impl ParsedGenerics {
+    pub(crate) fn parse(generics: &mut Generics) -> syn::Result<Self> {
+        let Generics {
+            lt_token,
+            params,
+            gt_token,
+            where_clause,
+        } = generics;
+        let mut errors = Errors::new();
+        let mut predicates: Vec<WherePredicate> = Vec::with_capacity(params.len());
+        let params = Punctuated::from_iter(params.pairs_mut().filter_map_pair_value_mut(|param| {
+            Some(match param {
+                GenericParam::Lifetime(param) => {
+                    errors.unwrap_or_default(HdlAttr::<LifetimeParamOptions>::parse_and_take_attr(
+                        &mut param.attrs,
+                    ));
+                    errors.error(param, "lifetime generics are not supported by #[hdl]");
+                    return None;
+                }
+                GenericParam::Type(TypeParam {
+                    attrs,
+                    ident,
+                    colon_token,
+                    bounds,
+                    eq_token,
+                    default,
+                }) => {
+                    let span = ident.span();
+                    let options = errors
+                        .unwrap_or_default(HdlAttr::<TypeParamOptions>::parse_and_take_attr(attrs))
+                        .unwrap_or_default();
+                    if !bounds.is_empty() {
+                        predicates.push(WherePredicate::Type(PredicateType {
+                            lifetimes: None,
+                            bounded_ty: parse_quote! { #ident },
+                            colon_token: colon_token.unwrap_or_else(|| Token![:](span)),
+                            bounds: bounds.clone(),
+                        }));
+                    }
+                    let default = default
+                        .as_mut()
+                        .and_then(|v| errors.ok(ParsedType::parse(v)));
+                    ParsedGenericParam::Type(ParsedTypeParam {
+                        attrs: attrs.clone(),
+                        options,
+                        ident: ident.clone(),
+                        default: default.map(|v| (eq_token.unwrap_or_else(|| Token![=](span)), v)),
+                    })
+                }
+                GenericParam::Const(ConstParam {
+                    attrs,
+                    const_token,
+                    ident,
+                    colon_token,
+                    ty,
+                    eq_token,
+                    default,
+                }) => {
+                    let options = errors
+                        .unwrap_or_default(HdlAttr::<ConstParamOptions>::parse_and_take_attr(attrs))
+                        .unwrap_or_default();
+                    todo!()
+                }
+            })
+        }));
+        if let Some(where_clause) = where_clause {
+            for predicate in &mut where_clause.predicates {
+                let WherePredicate::Type(PredicateType {
+                    lifetimes,
+                    bounded_ty,
+                    colon_token,
+                    bounds,
+                }) = predicate
+                else {
+                    errors.error(predicate, "unsupported where predicate kind");
+                    continue;
+                };
+                todo!();
+            }
+        }
+        errors.finish()?;
+        Ok(Self {
+            lt_token: *lt_token,
+            params,
+            gt_token: *gt_token,
+        })
+    }
+}
+
+impl ToTokens for ParsedGenerics {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        todo!()
+    }
+}
+
+#[derive(Debug, Clone)]
+pub(crate) struct ParsedGenericsImplGenerics<'a>(&'a ParsedGenerics);
+
+impl ToTokens for ParsedGenericsImplGenerics<'_> {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        todo!()
+    }
+}
+
+#[derive(Debug, Clone)]
+pub(crate) struct ParsedGenericsTurbofish<'a>(&'a ParsedGenerics);
+
+impl ToTokens for ParsedGenericsTurbofish<'_> {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        todo!()
+    }
+}
+
+#[derive(Debug, Clone)]
+pub(crate) struct ParsedGenericsTypeGenerics<'a>(&'a ParsedGenerics);
+
+impl ToTokens for ParsedGenericsTypeGenerics<'_> {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        todo!()
+    }
+}
+
+#[derive(Debug, Clone)]
+pub(crate) struct ParsedGenericsWhereClause<'a>(&'a ParsedGenerics);
+
+impl ToTokens for ParsedGenericsWhereClause<'_> {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        todo!()
+    }
+}
+
+pub trait AsTurbofish {
+    type Turbofish<'a>: 'a + ToTokens + Clone + fmt::Debug
+    where
+        Self: 'a;
+    fn as_turbofish(&self) -> Self::Turbofish<'_>;
+}
+
+impl AsTurbofish for TypeGenerics<'_> {
+    type Turbofish<'a> = Turbofish<'a> where Self: 'a;
+
+    fn as_turbofish(&self) -> Self::Turbofish<'_> {
+        TypeGenerics::as_turbofish(self)
+    }
+}
+
+impl AsTurbofish for ParsedGenericsTypeGenerics<'_> {
+    type Turbofish<'a> = ParsedGenericsTurbofish<'a>
+    where
+        Self: 'a;
+
+    fn as_turbofish(&self) -> Self::Turbofish<'_> {
+        ParsedGenericsTurbofish(self.0)
+    }
+}
+
+pub trait SplitForImpl {
+    type ImplGenerics<'a>: 'a + ToTokens + Clone + fmt::Debug
+    where
+        Self: 'a;
+    type TypeGenerics<'a>: 'a + AsTurbofish + ToTokens + Clone + fmt::Debug
+    where
+        Self: 'a;
+    type WhereClause<'a>: 'a + ToTokens + Clone + fmt::Debug
+    where
+        Self: 'a;
+    fn split_for_impl(
+        &self,
+    ) -> (
+        Self::ImplGenerics<'_>,
+        Self::TypeGenerics<'_>,
+        Self::WhereClause<'_>,
+    );
+}
+
+impl SplitForImpl for Generics {
+    type ImplGenerics<'a> = ImplGenerics<'a>;
+    type TypeGenerics<'a> = TypeGenerics<'a>;
+    type WhereClause<'a> = Option<&'a WhereClause>;
+    fn split_for_impl(
+        &self,
+    ) -> (
+        Self::ImplGenerics<'_>,
+        Self::TypeGenerics<'_>,
+        Self::WhereClause<'_>,
+    ) {
+        Generics::split_for_impl(&self)
+    }
+}
+
+impl SplitForImpl for ParsedGenerics {
+    type ImplGenerics<'a> = ParsedGenericsImplGenerics<'a>
+    where
+        Self: 'a;
+
+    type TypeGenerics<'a> = ParsedGenericsTypeGenerics<'a>
+    where
+        Self: 'a;
+
+    type WhereClause<'a> = ParsedGenericsWhereClause<'a>
+    where
+        Self: 'a;
+
+    fn split_for_impl(
+        &self,
+    ) -> (
+        Self::ImplGenerics<'_>,
+        Self::TypeGenerics<'_>,
+        Self::WhereClause<'_>,
+    ) {
+        (
+            ParsedGenericsImplGenerics(self),
+            ParsedGenericsTypeGenerics(self),
+            ParsedGenericsWhereClause(self),
+        )
+    }
+}
+
+#[derive(Debug, Clone)]
+pub(crate) enum MaybeParsed<P, U> {
+    Unrecognized(U),
+    Parsed(P),
+}
+
+impl<P: ToTokens, U: ToTokens> ToTokens for MaybeParsed<P, U> {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        match self {
+            MaybeParsed::Unrecognized(v) => v.to_tokens(tokens),
+            MaybeParsed::Parsed(v) => v.to_tokens(tokens),
+        }
+    }
+
+    fn to_token_stream(&self) -> TokenStream {
+        match self {
+            MaybeParsed::Unrecognized(v) => v.to_token_stream(),
+            MaybeParsed::Parsed(v) => v.to_token_stream(),
+        }
+    }
+
+    fn into_token_stream(self) -> TokenStream {
+        match self {
+            MaybeParsed::Unrecognized(v) => v.into_token_stream(),
+            MaybeParsed::Parsed(v) => v.into_token_stream(),
+        }
+    }
+}
+
+impl<P: AsTurbofish, U: AsTurbofish> AsTurbofish for MaybeParsed<P, U> {
+    type Turbofish<'a> = MaybeParsed<P::Turbofish<'a>, U::Turbofish<'a>>
+    where
+        Self: 'a;
+
+    fn as_turbofish(&self) -> Self::Turbofish<'_> {
+        match self {
+            MaybeParsed::Unrecognized(v) => MaybeParsed::Unrecognized(v.as_turbofish()),
+            MaybeParsed::Parsed(v) => MaybeParsed::Parsed(v.as_turbofish()),
+        }
+    }
+}
+
+impl<P: SplitForImpl, U: SplitForImpl> SplitForImpl for MaybeParsed<P, U> {
+    type ImplGenerics<'a> = MaybeParsed<P::ImplGenerics<'a>, U::ImplGenerics<'a>>
+    where
+        Self: 'a;
+    type TypeGenerics<'a> = MaybeParsed<P::TypeGenerics<'a>, U::TypeGenerics<'a>>
+    where
+        Self: 'a;
+    type WhereClause<'a> = MaybeParsed<P::WhereClause<'a>, U::WhereClause<'a>>
+    where
+        Self: 'a;
+
+    fn split_for_impl(
+        &self,
+    ) -> (
+        Self::ImplGenerics<'_>,
+        Self::TypeGenerics<'_>,
+        Self::WhereClause<'_>,
+    ) {
+        match self {
+            MaybeParsed::Unrecognized(v) => {
+                let (i, t, w) = v.split_for_impl();
+                (
+                    MaybeParsed::Unrecognized(i),
+                    MaybeParsed::Unrecognized(t),
+                    MaybeParsed::Unrecognized(w),
+                )
+            }
+            MaybeParsed::Parsed(v) => {
+                let (i, t, w) = v.split_for_impl();
+                (
+                    MaybeParsed::Parsed(i),
+                    MaybeParsed::Parsed(t),
+                    MaybeParsed::Parsed(w),
+                )
+            }
+        }
+    }
+}

crates/fayalite-proc-macros-impl/src/lib.rs

@@ -13,6 +13,9 @@ use syn::{
 };
 
 mod fold;
+mod hdl_bundle;
+mod hdl_enum;
+mod hdl_type_common;
 mod module;
 mod value_derive_common;
 mod value_derive_enum;
@@ -728,3 +731,15 @@ pub fn value_derive(item: TokenStream) -> syn::Result<TokenStream> {
         )),
     }
 }
+
+pub fn hdl_attr(attr: TokenStream, item: TokenStream) -> syn::Result<TokenStream> {
+    let item = syn::parse2::<Item>(quote! { #[hdl(#attr)] #item })?;
+    match item {
+        Item::Enum(item) => hdl_enum::hdl_enum(item),
+        Item::Struct(item) => hdl_bundle::hdl_bundle(item),
+        _ => Err(syn::Error::new(
+            Span::call_site(),
+            "top-level #[hdl] can only be used on structs or enums",
+        )),
+    }
+}

crates/fayalite-proc-macros-impl/src/module/transform_body.rs

@@ -1290,7 +1290,10 @@ impl Visitor {
                 memory,
                 paren,
                 ty_expr,
-            } => (paren, unwrap_or_static_type(ty_expr.as_ref(), memory.span())),
+            } => (
+                paren,
+                unwrap_or_static_type(ty_expr.as_ref(), memory.span()),
+            ),
             MemoryFn::MemoryArray {
                 memory_array,
                 paren,

crates/fayalite-proc-macros/src/lib.rs

@@ -24,3 +24,15 @@ pub fn value_derive(item: proc_macro::TokenStream) -> proc_macro::TokenStream {
         Err(err) => err.into_compile_error().into(),
     }
 }
+
+// intentionally not documented here, see `fayalite::hdl` for docs
+#[proc_macro_attribute]
+pub fn hdl(
+    attr: proc_macro::TokenStream,
+    item: proc_macro::TokenStream,
+) -> proc_macro::TokenStream {
+    match fayalite_proc_macros_impl::hdl_attr(attr.into(), item.into()) {
+        Ok(retval) => retval.into(),
+        Err(err) => err.into_compile_error().into(),
+    }
+}

crates/fayalite/src/array.rs

@@ -1,671 +1,185 @@
 // SPDX-License-Identifier: LGPL-3.0-or-later
 // See Notices.txt for copyright information
+
 use crate::{
-    bundle::{BundleType, BundleValue},
-    expr::{
-        ops::{ArrayIndex, ArrayLiteral, ExprIndex},
-        Expr, ToExpr,
-    },
-    intern::{Intern, Interned, InternedCompare, Memoize},
-    module::{
-        transform::visit::{Fold, Folder, Visit, Visitor},
-        ModuleBuilder, NormalModule,
-    },
+    expr::{ops::ArrayIndex, Expr, ToExpr},
+    int::{DynSize, KnownSize, Size},
+    intern::{Intern, Interned},
+    module::{ModuleBuilder, NormalModule},
     source_location::SourceLocation,
     ty::{
-        CanonicalType, CanonicalTypeKind, CanonicalValue, Connect, DynCanonicalType,
-        DynCanonicalValue, DynType, DynValueTrait, MatchVariantWithoutScope, StaticType,
-        StaticValue, Type, TypeEnum, Value, ValueEnum,
+        CanonicalType, MatchVariantWithoutScope, StaticType, Type, TypeProperties, TypeWithDeref,
     },
-    util::{ConstBool, GenericConstBool, MakeMutSlice},
-};
-use bitvec::{slice::BitSlice, vec::BitVec};
-use std::{
-    any::Any,
-    borrow::{Borrow, BorrowMut},
-    fmt,
-    hash::Hash,
-    marker::PhantomData,
-    ops::IndexMut,
-    sync::Arc,
+    util::ConstUsize,
 };
+use std::ops::Index;
 
-mod sealed {
-    pub trait Sealed {}
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
+struct ArrayImpl<T: Type, Len: Size> {
+    element: T,
+    len: Len::SizeType,
+    type_properties: TypeProperties,
 }
 
-pub trait ValueArrayOrSlice:
-    sealed::Sealed
-    + BorrowMut<[<Self as ValueArrayOrSlice>::Element]>
-    + AsRef<[<Self as ValueArrayOrSlice>::Element]>
-    + AsMut<[<Self as ValueArrayOrSlice>::Element]>
-    + Hash
-    + fmt::Debug
-    + Eq
-    + Send
-    + Sync
-    + 'static
-    + IndexMut<usize, Output = <Self as ValueArrayOrSlice>::Element>
-    + ToOwned
-    + InternedCompare
-{
-    type Element: Value<Type = <Self as ValueArrayOrSlice>::ElementType>;
-    type ElementType: Type<Value = <Self as ValueArrayOrSlice>::Element>;
-    type LenType: 'static + Copy + Ord + fmt::Debug + Hash + Send + Sync;
-    type Match: 'static
-        + Clone
-        + Eq
-        + fmt::Debug
-        + Hash
-        + Send
-        + Sync
-        + BorrowMut<[Expr<Self::Element>]>;
-    type MaskVA: ValueArrayOrSlice<
-            Element = <Self::ElementType as Type>::MaskValue,
-            ElementType = <Self::ElementType as Type>::MaskType,
-            LenType = Self::LenType,
-            MaskVA = Self::MaskVA,
-        > + ?Sized;
-    type IsStaticLen: GenericConstBool;
-    const FIXED_LEN_TYPE: Option<Self::LenType>;
-    fn make_match(array: Expr<Array<Self>>) -> Self::Match;
-    fn len_from_len_type(v: Self::LenType) -> usize;
-    #[allow(clippy::result_unit_err)]
-    fn try_len_type_from_len(v: usize) -> Result<Self::LenType, ()>;
-    fn len_type(&self) -> Self::LenType;
-    fn len(&self) -> usize;
-    fn is_empty(&self) -> bool;
-    fn iter(&self) -> std::slice::Iter<Self::Element> {
-        Borrow::<[_]>::borrow(self).iter()
-    }
-    fn clone_to_arc(&self) -> Arc<Self>;
-    fn arc_make_mut(v: &mut Arc<Self>) -> &mut Self;
-    fn arc_to_arc_slice(self: Arc<Self>) -> Arc<[Self::Element]>;
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
+pub struct ArrayType<T: Type = CanonicalType, Len: Size = DynSize> {
+    impl_: Interned<ArrayImpl<T, Len>>,
 }
 
-impl<T> sealed::Sealed for [T] {}
-
-impl<V: Value> ValueArrayOrSlice for [V]
-where
-    V::Type: Type<Value = V>,
-{
-    type Element = V;
-    type ElementType = V::Type;
-    type LenType = usize;
-    type Match = Box<[Expr<V>]>;
-    type MaskVA = [<Self::ElementType as Type>::MaskValue];
-    type IsStaticLen = ConstBool<false>;
-    const FIXED_LEN_TYPE: Option<Self::LenType> = None;
-
-    fn make_match(array: Expr<Array<Self>>) -> Self::Match {
-        (0..array.canonical_type().len())
-            .map(|index| ArrayIndex::<V::Type>::new_unchecked(array.canonical(), index).to_expr())
-            .collect()
-    }
-
-    fn len_from_len_type(v: Self::LenType) -> usize {
-        v
-    }
-
-    fn try_len_type_from_len(v: usize) -> Result<Self::LenType, ()> {
-        Ok(v)
-    }
-
-    fn len_type(&self) -> Self::LenType {
-        self.len()
-    }
-
-    fn len(&self) -> usize {
-        <[_]>::len(self)
-    }
-
-    fn is_empty(&self) -> bool {
-        <[_]>::is_empty(self)
-    }
-
-    fn clone_to_arc(&self) -> Arc<Self> {
-        Arc::from(self)
-    }
-
-    fn arc_make_mut(v: &mut Arc<Self>) -> &mut Self {
-        MakeMutSlice::make_mut_slice(v)
-    }
-
-    fn arc_to_arc_slice(self: Arc<Self>) -> Arc<[Self::Element]> {
-        self
+impl<T: Type, Len: Size> std::fmt::Debug for ArrayType<T, Len> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let ArrayImpl {
+            element, len: _, ..
+        } = *self.impl_;
+        write!(f, "Array<{element:?}, {}>", self.len())
     }
 }
 
-impl<T, const N: usize> sealed::Sealed for [T; N] {}
+pub type Array<
+    T = CanonicalType,
+    const LEN: usize = { <DynSize as crate::util::GenericConstUsize>::VALUE },
+> = ArrayType<T, ConstUsize<LEN>>;
 
-impl<V: Value, const N: usize> ValueArrayOrSlice for [V; N]
-where
-    V::Type: Type<Value = V>,
-{
-    type Element = V;
-    type ElementType = V::Type;
-    type LenType = ();
-    type Match = [Expr<V>; N];
-    type MaskVA = [<Self::ElementType as Type>::MaskValue; N];
-    type IsStaticLen = ConstBool<true>;
-    const FIXED_LEN_TYPE: Option<Self::LenType> = Some(());
+#[allow(non_upper_case_globals)]
+pub const Array: ArrayWithoutGenerics = ArrayWithoutGenerics;
 
-    fn make_match(array: Expr<Array<Self>>) -> Self::Match {
-        std::array::from_fn(|index| {
-            ArrayIndex::<V::Type>::new_unchecked(array.canonical(), index).to_expr()
-        })
-    }
-
-    fn len_from_len_type(_v: Self::LenType) -> usize {
-        N
-    }
-
-    fn try_len_type_from_len(v: usize) -> Result<Self::LenType, ()> {
-        if v == N {
-            Ok(())
-        } else {
-            Err(())
-        }
-    }
-
-    fn len_type(&self) -> Self::LenType {}
-
-    fn len(&self) -> usize {
-        N
-    }
-
-    fn is_empty(&self) -> bool {
-        N == 0
-    }
-
-    fn clone_to_arc(&self) -> Arc<Self> {
-        Arc::new(self.clone())
-    }
-
-    fn arc_make_mut(v: &mut Arc<Self>) -> &mut Self {
-        Arc::make_mut(v)
-    }
-
-    fn arc_to_arc_slice(self: Arc<Self>) -> Arc<[Self::Element]> {
-        self
-    }
-}
-
-#[derive(Debug, PartialEq, Eq, Hash)]
-pub struct ArrayType<VA: ValueArrayOrSlice + ?Sized> {
-    element: VA::ElementType,
-    len: VA::LenType,
-    bit_width: usize,
-}
-
-pub trait ArrayTypeTrait:
-    Type<
-        CanonicalType = ArrayType<[DynCanonicalValue]>,
-        Value = Array<<Self as ArrayTypeTrait>::ValueArrayOrSlice>,
-        CanonicalValue = Array<[DynCanonicalValue]>,
-        MaskType = ArrayType<
-            <<Self as ArrayTypeTrait>::ValueArrayOrSlice as ValueArrayOrSlice>::MaskVA,
-        >,
-    > + From<ArrayType<<Self as ArrayTypeTrait>::ValueArrayOrSlice>>
-    + Into<ArrayType<<Self as ArrayTypeTrait>::ValueArrayOrSlice>>
-    + BorrowMut<ArrayType<<Self as ArrayTypeTrait>::ValueArrayOrSlice>>
-    + sealed::Sealed
-    + Connect<Self>
-{
-    type ValueArrayOrSlice: ValueArrayOrSlice<Element = Self::Element, ElementType = Self::ElementType>
-        + ?Sized;
-    type Element: Value<Type = Self::ElementType>;
-    type ElementType: Type<Value = Self::Element>;
-}
-
-impl<VA: ValueArrayOrSlice + ?Sized> sealed::Sealed for ArrayType<VA> {}
-
-impl<VA: ValueArrayOrSlice + ?Sized> ArrayTypeTrait for ArrayType<VA> {
-    type ValueArrayOrSlice = VA;
-    type Element = VA::Element;
-    type ElementType = VA::ElementType;
-}
-
-impl<VA: ValueArrayOrSlice + ?Sized> Clone for ArrayType<VA> {
-    fn clone(&self) -> Self {
-        Self {
-            element: self.element.clone(),
-            len: self.len,
-            bit_width: self.bit_width,
-        }
-    }
-}
-
-impl<VA: ValueArrayOrSlice + ?Sized> Copy for ArrayType<VA> where VA::ElementType: Copy {}
-
-impl<VA: ValueArrayOrSlice + ?Sized> ArrayType<VA> {
-    pub fn element(&self) -> &VA::ElementType {
-        &self.element
-    }
-    pub fn len(&self) -> usize {
-        VA::len_from_len_type(self.len)
-    }
-    pub fn is_empty(&self) -> bool {
-        self.len() == 0
-    }
-    pub fn bit_width(&self) -> usize {
-        self.bit_width
-    }
-    pub fn into_slice_type(self) -> ArrayType<[VA::Element]> {
-        ArrayType {
-            len: self.len(),
-            element: self.element,
-            bit_width: self.bit_width,
-        }
-    }
-    #[track_caller]
-    pub fn new_with_len(element: VA::ElementType, len: usize) -> Self {
-        Self::new_with_len_type(
-            element,
-            VA::try_len_type_from_len(len).expect("length should match"),
-        )
-    }
-    #[track_caller]
-    pub fn new_with_len_type(element: VA::ElementType, len: VA::LenType) -> Self {
-        let Some(bit_width) = VA::len_from_len_type(len).checked_mul(element.bit_width()) else {
-            panic!("array is too big: bit-width overflowed");
+impl<T: Type, Len: Size> ArrayType<T, Len> {
+    pub fn new(element: T, len: Len::SizeType) -> Self {
+        let element_props = element.canonical().type_properties();
+        let type_properties = TypeProperties {
+            is_passive: element_props.is_passive,
+            is_storable: element_props.is_storable,
+            is_castable_from_bits: element_props.is_castable_from_bits,
+            bit_width: element_props
+                .bit_width
+                .checked_mul(Len::as_usize(len))
+                .expect("array too big"),
         };
-        ArrayType {
-            element,
-            len,
-            bit_width,
+        Self {
+            impl_: ArrayImpl {
+                element,
+                len,
+                type_properties,
+            }
+            .intern_sized(),
         }
     }
-}
-
-impl<VA: ValueArrayOrSlice + ?Sized, State: ?Sized + Folder> Fold<State> for ArrayType<VA>
-where
-    VA::ElementType: Fold<State>,
-{
-    fn fold(self, state: &mut State) -> Result<Self, State::Error> {
-        state.fold_array_type(self)
+    pub fn element(&self) -> &T {
+        &self.impl_.element
     }
-    fn default_fold(self, state: &mut State) -> Result<Self, State::Error> {
-        Ok(Self::new_with_len_type(self.element.fold(state)?, self.len))
+    pub fn len(self) -> usize {
+        Len::as_usize(self.impl_.len)
+    }
+    pub fn type_properties(self) -> TypeProperties {
+        self.impl_.type_properties
+    }
+    pub fn as_dyn_array(self) -> Array {
+        Array::new_dyn(self.element().canonical(), self.len())
     }
 }
 
-impl<VA: ValueArrayOrSlice + ?Sized, State: ?Sized + Visitor> Visit<State> for ArrayType<VA>
-where
-    VA::ElementType: Visit<State>,
-{
-    fn visit(&self, state: &mut State) -> Result<(), State::Error> {
-        state.visit_array_type(self)
-    }
-    fn default_visit(&self, state: &mut State) -> Result<(), State::Error> {
-        self.element.visit(state)
+impl<T: Type, Len: KnownSize> ArrayType<T, Len> {
+    pub fn new_static(element: T) -> Self {
+        Self::new(element, Len::SizeType::default())
     }
 }
 
-impl<V: Value<Type: Type<Value = V>>, const N: usize> ArrayType<[V; N]> {
-    pub fn new_array(element: V::Type) -> Self {
-        ArrayType::new_with_len_type(element, ())
-    }
-}
-
-impl<V: StaticValue, const N: usize> StaticType for ArrayType<[V; N]> {
+impl<T: StaticType, Len: KnownSize> StaticType for ArrayType<T, Len> {
     fn static_type() -> Self {
-        Self::new_array(StaticType::static_type())
+        Self::new_static(T::static_type())
     }
 }
 
-impl<V: Value<Type: Type<Value = V>>> ArrayType<[V]> {
-    pub fn new_slice(element: V::Type, len: usize) -> Self {
-        ArrayType::new_with_len_type(element, len)
+impl<T: Type> Array<T> {
+    pub fn new_dyn(element: T, len: usize) -> Self {
+        Self::new(element, len)
     }
 }
 
-impl<VA: ValueArrayOrSlice + ?Sized> Type for ArrayType<VA> {
-    type CanonicalType = ArrayType<[DynCanonicalValue]>;
-    type Value = Array<VA>;
-    type CanonicalValue = Array<[DynCanonicalValue]>;
-    type MaskType = ArrayType<VA::MaskVA>;
-    type MaskValue = Array<VA::MaskVA>;
-    type MatchVariant = VA::Match;
+impl<T: Type, Len: Size> Type for ArrayType<T, Len> {
+    type MaskType = ArrayType<T::MaskType, Len>;
+    type MatchVariant = Len::ArrayMatch<T>;
     type MatchActiveScope = ();
-    type MatchVariantAndInactiveScope = MatchVariantWithoutScope<VA::Match>;
+    type MatchVariantAndInactiveScope = MatchVariantWithoutScope<Len::ArrayMatch<T>>;
     type MatchVariantsIter = std::iter::Once<Self::MatchVariantAndInactiveScope>;
 
-    fn match_variants<IO: BundleValue>(
-        this: Expr<Self::Value>,
-        module_builder: &mut ModuleBuilder<IO, NormalModule>,
+    fn match_variants(
+        this: Expr<Self>,
+        module_builder: &mut ModuleBuilder<NormalModule>,
         source_location: SourceLocation,
-    ) -> Self::MatchVariantsIter
-    where
-        IO::Type: BundleType<Value = IO>,
-    {
+    ) -> Self::MatchVariantsIter {
+        let base = Expr::as_dyn_array(this);
+        let base_ty = Expr::ty(base);
         let _ = module_builder;
         let _ = source_location;
-        std::iter::once(MatchVariantWithoutScope(VA::make_match(this)))
+        let retval = Vec::from_iter(
+            (0..base_ty.len()).map(|i| ArrayIndex::new_unchecked(base, i).to_expr()),
+        );
+        std::iter::once(MatchVariantWithoutScope(
+            Len::ArrayMatch::<T>::try_from(retval)
+                .ok()
+                .expect("unreachable"),
+        ))
     }
 
     fn mask_type(&self) -> Self::MaskType {
-        #[derive(Clone, Hash, Eq, PartialEq)]
-        struct ArrayMaskTypeMemoize<T: ArrayTypeTrait>(PhantomData<T>);
-        impl<T: ArrayTypeTrait> Copy for ArrayMaskTypeMemoize<T> {}
-        impl<T: ArrayTypeTrait> Memoize for ArrayMaskTypeMemoize<T> {
-            type Input = ArrayType<T::ValueArrayOrSlice>;
-            type InputOwned = ArrayType<T::ValueArrayOrSlice>;
-            type Output = <ArrayType<T::ValueArrayOrSlice> as Type>::MaskType;
-
-            fn inner(self, input: &Self::Input) -> Self::Output {
-                ArrayType::new_with_len_type(input.element.mask_type(), input.len)
-            }
-        }
-        ArrayMaskTypeMemoize::<Self>(PhantomData).get(self)
+        ArrayType::new(self.element().mask_type(), self.impl_.len)
     }
 
-    fn canonical(&self) -> Self::CanonicalType {
-        ArrayType {
-            element: self.element.canonical_dyn(),
-            len: self.len(),
-            bit_width: self.bit_width,
-        }
+    fn canonical(&self) -> CanonicalType {
+        CanonicalType::Array(Array::new_dyn(self.element().canonical(), self.len()))
     }
 
-    fn source_location(&self) -> SourceLocation {
+    #[track_caller]
+    fn from_canonical(canonical_type: CanonicalType) -> Self {
+        let CanonicalType::Array(array) = canonical_type else {
+            panic!("expected array");
+        };
+        Self::new(
+            T::from_canonical(*array.element()),
+            Len::from_usize(array.len()),
+        )
+    }
+    fn source_location() -> SourceLocation {
         SourceLocation::builtin()
     }
+}
 
-    fn type_enum(&self) -> TypeEnum {
-        TypeEnum::ArrayType(self.canonical())
-    }
-
-    fn from_canonical_type(t: Self::CanonicalType) -> Self {
-        Self {
-            element: VA::ElementType::from_dyn_canonical_type(t.element),
-            len: VA::try_len_type_from_len(t.len).expect("length should match"),
-            bit_width: t.bit_width,
-        }
-    }
-
-    fn as_dyn_canonical_type_impl(this: &Self) -> Option<&dyn DynCanonicalType> {
-        Some(<dyn Any>::downcast_ref::<ArrayType<[DynCanonicalValue]>>(
-            this,
-        )?)
+impl<T: Type, Len: Size> TypeWithDeref for ArrayType<T, Len> {
+    fn expr_deref(this: &Expr<Self>) -> &Self::MatchVariant {
+        let base = Expr::as_dyn_array(*this);
+        let base_ty = Expr::ty(base);
+        let retval = Vec::from_iter(
+            (0..base_ty.len()).map(|i| ArrayIndex::new_unchecked(base, i).to_expr()),
+        );
+        Interned::<_>::into_inner(Intern::intern_sized(
+            Len::ArrayMatch::<T>::try_from(retval)
+                .ok()
+                .expect("unreachable"),
+        ))
     }
 }
 
-impl<Lhs: ValueArrayOrSlice + ?Sized, Rhs: ValueArrayOrSlice + ?Sized> Connect<ArrayType<Rhs>>
-    for ArrayType<Lhs>
-{
-}
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, Default)]
+pub struct ArrayWithoutGenerics;
 
-impl CanonicalType for ArrayType<[DynCanonicalValue]> {
-    const CANONICAL_TYPE_KIND: CanonicalTypeKind = CanonicalTypeKind::ArrayType;
-}
+impl<T: Type> Index<T> for ArrayWithoutGenerics {
+    type Output = ArrayWithoutLen<T>;
 
-#[derive(Debug, PartialEq, Eq, Hash)]
-pub struct Array<VA: ValueArrayOrSlice + ?Sized> {
-    element_ty: VA::ElementType,
-    value: Arc<VA>,
-}
-
-impl<VA: ValueArrayOrSlice + ?Sized> Clone for Array<VA> {
-    fn clone(&self) -> Self {
-        Self {
-            element_ty: self.element_ty.clone(),
-            value: self.value.clone(),
-        }
+    fn index(&self, element: T) -> &Self::Output {
+        Interned::<_>::into_inner(Intern::intern_sized(ArrayWithoutLen { element }))
     }
 }
 
-impl<VA: ValueArrayOrSlice + ?Sized> ToExpr for Array<VA> {
-    type Type = ArrayType<VA>;
-
-    fn ty(&self) -> Self::Type {
-        ArrayType::new_with_len_type(self.element_ty.clone(), self.value.len_type())
-    }
-
-    fn to_expr(&self) -> Expr<<Self::Type as Type>::Value> {
-        Expr::from_value(self)
-    }
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
+pub struct ArrayWithoutLen<T: Type> {
+    element: T,
 }
 
-impl<VA: ValueArrayOrSlice + ?Sized> Value for Array<VA> {
-    fn to_canonical(&self) -> <Self::Type as Type>::CanonicalValue {
-        Array {
-            element_ty: self.element_ty.canonical_dyn(),
-            value: AsRef::<[_]>::as_ref(&*self.value)
-                .iter()
-                .map(|v| v.to_canonical_dyn())
-                .collect(),
-        }
-    }
-    fn to_bits_impl(this: &Self) -> Interned<BitSlice> {
-        #[derive(Hash, Eq, PartialEq)]
-        struct ArrayToBitsMemoize<VA: ValueArrayOrSlice + ?Sized>(PhantomData<VA>);
-        impl<VA: ValueArrayOrSlice + ?Sized> Clone for ArrayToBitsMemoize<VA> {
-            fn clone(&self) -> Self {
-                *self
-            }
-        }
-        impl<VA: ValueArrayOrSlice + ?Sized> Copy for ArrayToBitsMemoize<VA> {}
-        impl<VA: ValueArrayOrSlice + ?Sized> Memoize for ArrayToBitsMemoize<VA> {
-            type Input = Array<VA>;
-            type InputOwned = Array<VA>;
-            type Output = Interned<BitSlice>;
+impl<T: Type> Index<usize> for ArrayWithoutLen<T> {
+    type Output = Array<T>;
 
-            fn inner(self, input: &Self::Input) -> Self::Output {
-                let mut bits = BitVec::with_capacity(input.ty().bit_width());
-                for element in AsRef::<[_]>::as_ref(&*input.value).iter() {
-                    bits.extend_from_bitslice(&element.to_bits());
-                }
-                Intern::intern_owned(bits)
-            }
-        }
-        ArrayToBitsMemoize::<VA>(PhantomData).get(this)
-    }
-}
-
-impl CanonicalValue for Array<[DynCanonicalValue]> {
-    fn value_enum_impl(this: &Self) -> ValueEnum {
-        ValueEnum::Array(this.clone())
-    }
-    fn to_bits_impl(this: &Self) -> Interned<BitSlice> {
-        Value::to_bits_impl(this)
-    }
-}
-
-impl<VA: ValueArrayOrSlice + ?Sized> Array<VA> {
-    pub fn element_ty(&self) -> &VA::ElementType {
-        &self.element_ty
-    }
-    pub fn len(&self) -> usize {
-        VA::len_from_len_type(self.value.len_type())
-    }
-    pub fn is_empty(&self) -> bool {
-        self.len() == 0
-    }
-    pub fn value(&self) -> &Arc<VA> {
-        &self.value
-    }
-    pub fn set_element(&mut self, index: usize, element: VA::Element) {
-        assert_eq!(self.element_ty, element.ty());
-        VA::arc_make_mut(&mut self.value)[index] = element;
-    }
-    pub fn new(element_ty: VA::ElementType, value: Arc<VA>) -> Self {
-        for element in value.iter() {
-            assert_eq!(element_ty, element.ty());
-        }
-        Self { element_ty, value }
-    }
-    pub fn into_slice(self) -> Array<[VA::Element]> {
-        Array {
-            element_ty: self.element_ty,
-            value: self.value.arc_to_arc_slice(),
-        }
-    }
-}
-
-impl<VA: ValueArrayOrSlice + ?Sized, T: Into<Arc<VA>>> From<T> for Array<VA>
-where
-    VA::Element: StaticValue,
-{
-    fn from(value: T) -> Self {
-        Self::new(StaticType::static_type(), value.into())
-    }
-}
-
-impl<E: ToExpr<Type = T>, T: StaticType<MaskType: StaticType>> ToExpr for [E] {
-    type Type = ArrayType<[T::Value]>;
-
-    fn ty(&self) -> Self::Type {
-        ArrayType::new_with_len_type(StaticType::static_type(), self.len())
-    }
-
-    fn to_expr(&self) -> Expr<<Self::Type as Type>::Value> {
-        let elements = Intern::intern_owned(Vec::from_iter(
-            self.iter().map(|v| v.to_expr().to_canonical_dyn()),
-        ));
-        ArrayLiteral::new_unchecked(elements, self.ty()).to_expr()
-    }
-}
-
-impl<E: ToExpr<Type = T>, T: StaticType<MaskType: StaticType>> ToExpr for Vec<E> {
-    type Type = ArrayType<[T::Value]>;
-
-    fn ty(&self) -> Self::Type {
-        <[E]>::ty(self)
-    }
-
-    fn to_expr(&self) -> Expr<<Self::Type as Type>::Value> {
-        <[E]>::to_expr(self)
-    }
-}
-
-impl<E: ToExpr<Type = T>, T: StaticType<MaskType: StaticType>, const N: usize> ToExpr for [E; N] {
-    type Type = ArrayType<[T::Value; N]>;
-
-    fn ty(&self) -> Self::Type {
-        ArrayType::new_with_len_type(StaticType::static_type(), ())
-    }
-
-    fn to_expr(&self) -> Expr<<Self::Type as Type>::Value> {
-        let elements = Intern::intern_owned(Vec::from_iter(
-            self.iter().map(|v| v.to_expr().to_canonical_dyn()),
-        ));
-        ArrayLiteral::new_unchecked(elements, self.ty()).to_expr()
-    }
-}
-
-#[derive(Clone, Debug)]
-pub struct ArrayIntoIter<VA: ValueArrayOrSlice> {
-    array: Arc<VA>,
-    indexes: std::ops::Range<usize>,
-}
-
-impl<VA: ValueArrayOrSlice> Iterator for ArrayIntoIter<VA> {
-    type Item = VA::Element;
-
-    fn next(&mut self) -> Option<Self::Item> {
-        Some(self.array[self.indexes.next()?].clone())
-    }
-
-    fn size_hint(&self) -> (usize, Option<usize>) {
-        self.indexes.size_hint()
-    }
-}
-
-impl<VA: ValueArrayOrSlice> std::iter::FusedIterator for ArrayIntoIter<VA> {}
-
-impl<VA: ValueArrayOrSlice> ExactSizeIterator for ArrayIntoIter<VA> {}
-
-impl<VA: ValueArrayOrSlice> DoubleEndedIterator for ArrayIntoIter<VA> {
-    fn next_back(&mut self) -> Option<Self::Item> {
-        Some(self.array[self.indexes.next_back()?].clone())
-    }
-}
-
-impl<VA: ValueArrayOrSlice> Array<VA> {
-    pub fn iter(&self) -> std::slice::Iter<'_, VA::Element> {
-        self.value.iter()
-    }
-}
-
-impl<'a, VA: ValueArrayOrSlice> IntoIterator for &'a Array<VA> {
-    type Item = &'a VA::Element;
-    type IntoIter = std::slice::Iter<'a, VA::Element>;
-
-    fn into_iter(self) -> Self::IntoIter {
-        self.value.iter()
-    }
-}
-
-impl<VA: ValueArrayOrSlice> IntoIterator for Array<VA> {
-    type Item = VA::Element;
-    type IntoIter = ArrayIntoIter<VA>;
-
-    fn into_iter(self) -> Self::IntoIter {
-        ArrayIntoIter {
-            indexes: 0..self.len(),
-            array: self.value,
-        }
-    }
-}
-
-#[derive(Clone, Debug)]
-pub struct ArrayExprIter<VA: ValueArrayOrSlice> {
-    array: Expr<Array<VA>>,
-    indexes: std::ops::Range<usize>,
-}
-
-impl<VA: ValueArrayOrSlice> Iterator for ArrayExprIter<VA> {
-    type Item = Expr<VA::Element>;
-
-    fn next(&mut self) -> Option<Self::Item> {
-        Some(ExprIndex::expr_index(self.array, self.indexes.next()?))
-    }
-
-    fn size_hint(&self) -> (usize, Option<usize>) {
-        self.indexes.size_hint()
-    }
-}
-
-impl<VA: ValueArrayOrSlice> std::iter::FusedIterator for ArrayExprIter<VA> {}
-
-impl<VA: ValueArrayOrSlice> ExactSizeIterator for ArrayExprIter<VA> {}
-
-impl<VA: ValueArrayOrSlice> DoubleEndedIterator for ArrayExprIter<VA> {
-    fn next_back(&mut self) -> Option<Self::Item> {
-        Some(ExprIndex::expr_index(self.array, self.indexes.next_back()?))
-    }
-}
-
-impl<VA: ValueArrayOrSlice> IntoIterator for Expr<Array<VA>> {
-    type Item = Expr<VA::Element>;
-    type IntoIter = ArrayExprIter<VA>;
-
-    fn into_iter(self) -> Self::IntoIter {
-        self.iter()
-    }
-}
-
-impl<VA: ValueArrayOrSlice> IntoIterator for &'_ Expr<Array<VA>> {
-    type Item = Expr<VA::Element>;
-    type IntoIter = ArrayExprIter<VA>;
-
-    fn into_iter(self) -> Self::IntoIter {
-        self.iter()
-    }
-}
-
-impl<VA: ValueArrayOrSlice> Expr<Array<VA>> {
-    pub fn len(self) -> usize {
-        self.canonical_type().len()
-    }
-    pub fn is_empty(self) -> bool {
-        self.canonical_type().is_empty()
-    }
-    pub fn iter(self) -> ArrayExprIter<VA> {
-        ArrayExprIter {
-            indexes: 0..self.len(),
-            array: self,
-        }
+    fn index(&self, len: usize) -> &Self::Output {
+        Interned::<_>::into_inner(Intern::intern_sized(Array::new_dyn(self.element, len)))
     }
 }

crates/fayalite/src/enum_.rs

@@ -1,150 +1,58 @@
 // SPDX-License-Identifier: LGPL-3.0-or-later
 // See Notices.txt for copyright information
-#![allow(clippy::type_complexity)]
+
 use crate::{
-    bundle::{BundleValue, TypeHintTrait},
     expr::{ops::VariantAccess, Expr, ToExpr},
-    int::{UInt, UIntType},
-    intern::{Intern, Interned, MemoizeGeneric},
+    hdl,
+    int::Bool,
+    intern::{Intern, Interned},
     module::{
         EnumMatchVariantAndInactiveScopeImpl, EnumMatchVariantsIterImpl, ModuleBuilder,
         NormalModule, Scope,
     },
     source_location::SourceLocation,
-    ty::{
-        CanonicalType, CanonicalTypeKind, CanonicalValue, Connect, DynCanonicalType,
-        DynCanonicalValue, DynType, MatchVariantAndInactiveScope, Type, TypeEnum, Value, ValueEnum,
-    },
+    ty::{CanonicalType, MatchVariantAndInactiveScope, Type, TypeProperties},
 };
-use bitvec::{order::Lsb0, slice::BitSlice, vec::BitVec, view::BitView};
 use hashbrown::HashMap;
-use std::{
-    borrow::Cow,
-    fmt,
-    hash::{Hash, Hasher},
-    iter::FusedIterator,
-    marker::PhantomData,
-};
+use std::iter::FusedIterator;
 
-#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq)]
-pub struct VariantType<T> {
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
+pub struct EnumVariant {
     pub name: Interned<str>,
-    pub ty: Option<T>,
-}
-
-pub struct FmtDebugInEnum<'a, T>(&'a VariantType<T>);
-
-impl<T: fmt::Debug> fmt::Debug for FmtDebugInEnum<'_, T> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        let VariantType { name, ref ty } = *self.0;
-        if let Some(ty) = ty {
-            write!(f, "{name}({ty:?})")
-        } else {
-            write!(f, "{name}")
-        }
-    }
-}
-
-impl<T: fmt::Debug> fmt::Display for FmtDebugInEnum<'_, T> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt::Debug::fmt(self, f)
-    }
-}
-
-impl<T> VariantType<T> {
-    pub fn map_opt_ty<U, F: FnOnce(Option<T>) -> Option<U>>(self, f: F) -> VariantType<U> {
-        let Self { name, ty } = self;
-        VariantType { name, ty: f(ty) }
-    }
-    pub fn map_ty<U, F: FnOnce(T) -> U>(self, f: F) -> VariantType<U> {
-        let Self { name, ty } = self;
-        VariantType {
-            name,
-            ty: ty.map(f),
-        }
-    }
-    pub fn as_ref_ty(&self) -> VariantType<&T> {
-        VariantType {
-            name: self.name,
-            ty: self.ty.as_ref(),
-        }
-    }
-    pub fn fmt_debug_in_enum(&self) -> FmtDebugInEnum<T> {
-        FmtDebugInEnum(self)
-    }
-}
-
-impl<T: Type> VariantType<T> {
-    pub fn canonical(&self) -> VariantType<T::CanonicalType> {
-        self.as_ref_ty().map_ty(T::canonical)
-    }
-    pub fn to_dyn(&self) -> VariantType<Interned<dyn DynType>> {
-        self.as_ref_ty().map_ty(T::to_dyn)
-    }
-    pub fn canonical_dyn(&self) -> VariantType<Interned<dyn DynCanonicalType>> {
-        self.as_ref_ty().map_ty(T::canonical_dyn)
-    }
-}
-
-impl VariantType<Interned<dyn DynCanonicalType>> {
-    pub fn from_canonical_type_helper_has_value<T: Type>(self, expected_name: &str) -> T {
-        assert_eq!(&*self.name, expected_name, "variant name doesn't match");
-        let Some(ty) = self.ty else {
-            panic!("variant {expected_name} has no value but a value is expected");
-        };
-        T::from_dyn_canonical_type(ty)
-    }
-    pub fn from_canonical_type_helper_no_value(self, expected_name: &str) {
-        assert_eq!(&*self.name, expected_name, "variant name doesn't match");
-        assert!(
-            self.ty.is_none(),
-            "variant {expected_name} has a value but is expected to have no value"
-        );
-    }
+    pub ty: Option<CanonicalType>,
 }
 
 #[derive(Clone, Eq)]
-struct DynEnumTypeImpl {
-    variants: Interned<[VariantType<Interned<dyn DynCanonicalType>>]>,
+struct EnumImpl {
+    variants: Interned<[EnumVariant]>,
     name_indexes: HashMap<Interned<str>, usize>,
-    bit_width: usize,
-    is_storable: bool,
-    is_castable_from_bits: bool,
+    type_properties: TypeProperties,
 }
 
-impl fmt::Debug for DynEnumTypeImpl {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "DynEnumType ")?;
-        f.debug_set()
-            .entries(
-                self.variants
-                    .iter()
-                    .map(|variant| variant.fmt_debug_in_enum()),
-            )
+impl std::fmt::Debug for EnumImpl {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("Enum")
+            .field("variants", &self.variants)
+            .field("name_indexes", &self.name_indexes)
+            .field("type_properties", &self.type_properties)
             .finish()
     }
 }
 
-impl PartialEq for DynEnumTypeImpl {
+impl std::hash::Hash for EnumImpl {
+    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
+        self.variants.hash(state);
+    }
+}
+
+impl PartialEq for EnumImpl {
     fn eq(&self, other: &Self) -> bool {
         self.variants == other.variants
     }
 }
 
-impl Hash for DynEnumTypeImpl {
-    fn hash<H: Hasher>(&self, state: &mut H) {
-        self.variants.hash(state);
-    }
-}
-
-#[derive(Copy, Clone, Hash, PartialEq, Eq)]
-pub struct DynEnumType(Interned<DynEnumTypeImpl>);
-
-impl fmt::Debug for DynEnumType {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        self.0.fmt(f)
-    }
-}
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
+pub struct Enum(Interned<EnumImpl>);
 
 fn discriminant_bit_width_impl(variant_count: usize) -> usize {
     variant_count
@@ -153,38 +61,47 @@ fn discriminant_bit_width_impl(variant_count: usize) -> usize {
         .unwrap_or(0) as usize
 }
 
-impl DynEnumType {
+impl Enum {
     #[track_caller]
-    pub fn new(variants: Interned<[VariantType<Interned<dyn DynCanonicalType>>]>) -> Self {
+    pub fn new(variants: Interned<[EnumVariant]>) -> Self {
         assert!(!variants.is_empty(), "zero-variant enums aren't yet supported: https://github.com/chipsalliance/firrtl-spec/issues/208");
         let mut name_indexes = HashMap::with_capacity(variants.len());
-        let mut body_bit_width = 0usize;
-        let mut is_storable = true;
-        let mut is_castable_from_bits = true;
-        for (index, &VariantType { name, ty }) in variants.iter().enumerate() {
-            if let Some(old_index) = name_indexes.insert(name, index) {
+        let mut type_properties = TypeProperties {
+            is_passive: true,
+            is_storable: true,
+            is_castable_from_bits: true,
+            bit_width: 0,
+        };
+        for (index, EnumVariant { name, ty }) in variants.iter().enumerate() {
+            if let Some(old_index) = name_indexes.insert(*name, index) {
                 panic!("duplicate variant name {name:?}: at both index {old_index} and {index}");
             }
             if let Some(ty) = ty {
-                assert!(
-                    ty.is_passive(),
-                    "variant type must be a passive type: {ty:?}"
-                );
-                body_bit_width = body_bit_width.max(ty.bit_width());
-                is_storable &= ty.is_storable();
-                is_castable_from_bits &= ty.is_castable_from_bits();
+                let TypeProperties {
+                    is_passive,
+                    is_storable,
+                    is_castable_from_bits,
+                    bit_width,
+                } = ty.type_properties();
+                assert!(is_passive, "variant type must be a passive type: {ty:?}");
+                type_properties = TypeProperties {
+                    is_passive: true,
+                    is_storable: type_properties.is_storable & is_storable,
+                    is_castable_from_bits: type_properties.is_castable_from_bits
+                        & is_castable_from_bits,
+                    bit_width: type_properties.bit_width.max(bit_width),
+                };
             }
         }
-        let bit_width = body_bit_width
+        type_properties.bit_width = type_properties
+            .bit_width
             .checked_add(discriminant_bit_width_impl(variants.len()))
             .unwrap_or_else(|| panic!("enum is too big: bit-width overflowed"));
         Self(
-            DynEnumTypeImpl {
+            EnumImpl {
                 variants,
                 name_indexes,
-                bit_width,
-                is_storable,
-                is_castable_from_bits,
+                type_properties,
             }
             .intern_sized(),
         )
@@ -192,233 +109,31 @@ impl DynEnumType {
     pub fn discriminant_bit_width(self) -> usize {
         discriminant_bit_width_impl(self.variants().len())
     }
-    pub fn is_passive(self) -> bool {
-        true
-    }
-    pub fn is_storable(self) -> bool {
-        self.0.is_storable
-    }
-    pub fn is_castable_from_bits(self) -> bool {
-        self.0.is_castable_from_bits
-    }
-    pub fn bit_width(self) -> usize {
-        self.0.bit_width
+    pub fn type_properties(self) -> TypeProperties {
+        self.0.type_properties
     }
     pub fn name_indexes(&self) -> &HashMap<Interned<str>, usize> {
         &self.0.name_indexes
     }
 }
 
-#[derive(Debug, Clone, Hash, PartialEq, Eq)]
-pub struct DynEnum {
-    ty: DynEnumType,
-    variant_index: usize,
-    variant_value: Option<DynCanonicalValue>,
-}
-
-impl DynEnum {
-    #[track_caller]
-    pub fn new_by_index(
-        ty: DynEnumType,
-        variant_index: usize,
-        variant_value: Option<DynCanonicalValue>,
-    ) -> Self {
-        let variant = ty.variants()[variant_index];
-        assert_eq!(
-            variant_value.as_ref().map(|v| v.ty()),
-            variant.ty,
-            "variant value doesn't match type"
-        );
-        Self {
-            ty,
-            variant_index,
-            variant_value,
-        }
-    }
-    #[track_caller]
-    pub fn new_by_name(
-        ty: DynEnumType,
-        variant_name: Interned<str>,
-        variant_value: Option<DynCanonicalValue>,
-    ) -> Self {
-        let variant_index = ty.name_indexes()[&variant_name];
-        Self::new_by_index(ty, variant_index, variant_value)
-    }
-    pub fn variant_index(&self) -> usize {
-        self.variant_index
-    }
-    pub fn variant_value(&self) -> &Option<DynCanonicalValue> {
-        &self.variant_value
-    }
-    pub fn variant_with_type(&self) -> VariantType<Interned<dyn DynCanonicalType>> {
-        self.ty.variants()[self.variant_index]
-    }
-    pub fn variant_name(&self) -> Interned<str> {
-        self.variant_with_type().name
-    }
-    pub fn variant_type(&self) -> Option<Interned<dyn DynCanonicalType>> {
-        self.variant_with_type().ty
-    }
-    pub fn variant_with_value(&self) -> VariantType<&DynCanonicalValue> {
-        self.variant_with_type()
-            .map_opt_ty(|_| self.variant_value.as_ref())
-    }
-}
-
-#[derive(Copy, Clone, Eq, PartialEq, Hash, Debug)]
-pub struct VariantsHint {
-    pub known_variants: Interned<[VariantType<Interned<dyn TypeHintTrait>>]>,
-    pub more_variants: bool,
-}
-
-impl VariantsHint {
-    pub fn new(
-        known_variants: impl IntoIterator<Item = VariantType<Interned<dyn TypeHintTrait>>>,
-        more_variants: bool,
-    ) -> Self {
-        let known_variants = Intern::intern_owned(Vec::from_iter(known_variants));
-        Self {
-            known_variants,
-            more_variants,
-        }
-    }
-    pub fn check_variant(
-        self,
-        index: usize,
-        variant: VariantType<&dyn DynType>,
-    ) -> Result<(), String> {
-        let Some(&known_variant) = self.known_variants.get(index) else {
-            return if self.more_variants {
-                Ok(())
-            } else {
-                Err(format!(
-                    "too many variants: name={:?} index={index}",
-                    variant.name
-                ))
-            };
-        };
-        let VariantType {
-            name: known_name,
-            ty: type_hint,
-        } = known_variant;
-        let VariantType { name, ty } = variant;
-        if name != known_name {
-            Err(format!(
-                "wrong variant name {name:?}, expected {known_name:?}"
-            ))
-        } else {
-            match (ty, type_hint) {
-                (Some(ty), Some(type_hint)) => type_hint.matches(ty),
-                (None, None) => Ok(()),
-                (None, Some(_)) => Err(format!(
-                    "expected variant {name:?} to have type, no type provided"
-                )),
-                (Some(_), None) => Err(format!(
-                    "expected variant {name:?} to have no type, but a type was provided"
-                )),
-            }
-        }
-    }
-}
-
 pub trait EnumType:
     Type<
-        CanonicalType = DynEnumType,
-        CanonicalValue = DynEnum,
-        MaskType = UIntType<1>,
-        MaskValue = UInt<1>,
-        MatchActiveScope = Scope,
-        MatchVariantAndInactiveScope = EnumMatchVariantAndInactiveScope<Self>,
-        MatchVariantsIter = EnumMatchVariantsIter<Self>,
-    > + Connect<Self>
-where
-    Self::Value: EnumValue + ToExpr<Type = Self>,
+    MaskType = Bool,
+    MatchActiveScope = Scope,
+    MatchVariantAndInactiveScope = EnumMatchVariantAndInactiveScope<Self>,
+    MatchVariantsIter = EnumMatchVariantsIter<Self>,
+>
 {
-    type Builder;
+    fn variants(&self) -> Interned<[EnumVariant]>;
     fn match_activate_scope(
         v: Self::MatchVariantAndInactiveScope,
     ) -> (Self::MatchVariant, Self::MatchActiveScope);
-    fn builder() -> Self::Builder;
-    fn variants(&self) -> Interned<[VariantType<Interned<dyn DynCanonicalType>>]>;
-    fn variants_hint() -> VariantsHint;
-    #[allow(clippy::result_unit_err)]
-    fn variant_to_bits<VariantValue: ToExpr + Eq + Hash + Send + Sync + 'static + Clone>(
-        &self,
-        variant_index: usize,
-        variant_value: Option<&VariantValue>,
-    ) -> Result<Interned<BitSlice>, ()> {
-        #[derive(Hash, Eq, PartialEq)]
-        struct VariantToBitsMemoize<E, V>(PhantomData<(E, V)>);
-        impl<E, V> Clone for VariantToBitsMemoize<E, V> {
-            fn clone(&self) -> Self {
-                *self
-            }
-        }
-        impl<E, V> Copy for VariantToBitsMemoize<E, V> {}
-        impl<
-                E: EnumType<Value: EnumValue<Type = E>>,
-                V: ToExpr + Eq + Hash + Send + Sync + 'static + Clone,
-            > MemoizeGeneric for VariantToBitsMemoize<E, V>
-        {
-            type InputRef<'a> = (&'a E, usize, Option<&'a V>);
-            type InputOwned = (E, usize, Option<V>);
-            type InputCow<'a> = (Cow<'a, E>, usize, Option<Cow<'a, V>>);
-            type Output = Result<Interned<BitSlice>, ()>;
-
-            fn input_borrow(input: &Self::InputOwned) -> Self::InputRef<'_> {
-                (&input.0, input.1, input.2.as_ref())
-            }
-            fn input_eq(a: Self::InputRef<'_>, b: Self::InputRef<'_>) -> bool {
-                a == b
-            }
-            fn input_cow_into_owned(input: Self::InputCow<'_>) -> Self::InputOwned {
-                (input.0.into_owned(), input.1, input.2.map(Cow::into_owned))
-            }
-            fn input_cow_borrow<'a>(input: &'a Self::InputCow<'_>) -> Self::InputRef<'a> {
-                (&input.0, input.1, input.2.as_deref())
-            }
-            fn input_cow_from_owned<'a>(input: Self::InputOwned) -> Self::InputCow<'a> {
-                (Cow::Owned(input.0), input.1, input.2.map(Cow::Owned))
-            }
-            fn input_cow_from_ref(input: Self::InputRef<'_>) -> Self::InputCow<'_> {
-                (Cow::Borrowed(input.0), input.1, input.2.map(Cow::Borrowed))
-            }
-            fn inner(self, input: Self::InputRef<'_>) -> Self::Output {
-                let (ty, variant_index, variant_value) = input;
-                let ty = ty.canonical();
-                let mut bits = BitVec::with_capacity(ty.bit_width());
-                bits.extend_from_bitslice(
-                    &variant_index.view_bits::<Lsb0>()[..ty.discriminant_bit_width()],
-                );
-                if let Some(variant_value) = variant_value {
-                    bits.extend_from_bitslice(&variant_value.to_expr().to_literal_bits()?);
-                }
-                bits.resize(ty.bit_width(), false);
-                Ok(Intern::intern_owned(bits))
-            }
-        }
-        VariantToBitsMemoize::<Self, VariantValue>(PhantomData).get((
-            self,
-            variant_index,
-            variant_value,
-        ))
-    }
 }
 
-pub trait EnumValue: Value
-where
-    <Self as ToExpr>::Type: EnumType<Value = Self>,
-{
-}
+pub struct EnumMatchVariantAndInactiveScope<T: EnumType>(EnumMatchVariantAndInactiveScopeImpl<T>);
 
-pub struct EnumMatchVariantAndInactiveScope<T: EnumType>(EnumMatchVariantAndInactiveScopeImpl<T>)
-where
-    T::Value: EnumValue<Type = T>;
-
-impl<T: EnumType> MatchVariantAndInactiveScope for EnumMatchVariantAndInactiveScope<T>
-where
-    T::Value: EnumValue<Type = T>,
-{
+impl<T: EnumType> MatchVariantAndInactiveScope for EnumMatchVariantAndInactiveScope<T> {
     type MatchVariant = T::MatchVariant;
     type MatchActiveScope = Scope;
 
@@ -427,36 +142,22 @@ where
     }
 }
 
-impl<T: EnumType> EnumMatchVariantAndInactiveScope<T>
-where
-    T::Value: EnumValue<Type = T>,
-{
-    pub fn variant_access(&self) -> Interned<VariantAccess<T, Interned<dyn DynCanonicalType>>> {
+impl<T: EnumType> EnumMatchVariantAndInactiveScope<T> {
+    pub fn variant_access(&self) -> Interned<VariantAccess> {
         self.0.variant_access()
     }
-    pub fn activate(
-        self,
-    ) -> (
-        Interned<VariantAccess<T, Interned<dyn DynCanonicalType>>>,
-        Scope,
-    ) {
+    pub fn activate(self) -> (Interned<VariantAccess>, Scope) {
         self.0.activate()
     }
 }
 
 #[derive(Clone)]
-pub struct EnumMatchVariantsIter<T: EnumType>
-where
-    T::Value: EnumValue<Type = T>,
-{
+pub struct EnumMatchVariantsIter<T: EnumType> {
     pub(crate) inner: EnumMatchVariantsIterImpl<T>,
     pub(crate) variant_index: std::ops::Range<usize>,
 }
 
-impl<T: EnumType> Iterator for EnumMatchVariantsIter<T>
-where
-    T::Value: EnumValue<Type = T>,
-{
+impl<T: EnumType> Iterator for EnumMatchVariantsIter<T> {
     type Item = EnumMatchVariantAndInactiveScope<T>;
 
     fn next(&mut self) -> Option<Self::Item> {
@@ -470,21 +171,15 @@ where
     }
 }
 
-impl<T: EnumType> ExactSizeIterator for EnumMatchVariantsIter<T>
-where
-    T::Value: EnumValue<Type = T>,
-{
+impl<T: EnumType> ExactSizeIterator for EnumMatchVariantsIter<T> {
     fn len(&self) -> usize {
         self.variant_index.len()
     }
 }
 
-impl<T: EnumType> FusedIterator for EnumMatchVariantsIter<T> where T::Value: EnumValue<Type = T> {}
+impl<T: EnumType> FusedIterator for EnumMatchVariantsIter<T> {}
 
-impl<T: EnumType> DoubleEndedIterator for EnumMatchVariantsIter<T>
-where
-    T::Value: EnumValue<Type = T>,
-{
+impl<T: EnumType> DoubleEndedIterator for EnumMatchVariantsIter<T> {
     fn next_back(&mut self) -> Option<Self::Item> {
         self.variant_index.next_back().map(|variant_index| {
             EnumMatchVariantAndInactiveScope(self.inner.for_variant_index(variant_index))
@@ -492,129 +187,55 @@ where
     }
 }
 
-impl Type for DynEnumType {
-    type CanonicalType = DynEnumType;
-    type Value = DynEnum;
-    type CanonicalValue = DynEnum;
-    type MaskType = UIntType<1>;
-    type MaskValue = UInt<1>;
-    type MatchVariant = Option<Expr<DynCanonicalValue>>;
-    type MatchActiveScope = Scope;
-    type MatchVariantAndInactiveScope = EnumMatchVariantAndInactiveScope<Self>;
-    type MatchVariantsIter = EnumMatchVariantsIter<Self>;
-
-    fn match_variants<IO: BundleValue>(
-        this: Expr<Self::Value>,
-        module_builder: &mut ModuleBuilder<IO, NormalModule>,
-        source_location: SourceLocation,
-    ) -> Self::MatchVariantsIter
-    where
-        IO::Type: crate::bundle::BundleType<Value = IO>,
-    {
-        module_builder.enum_match_variants_helper(this, source_location)
-    }
-
-    fn mask_type(&self) -> Self::MaskType {
-        UIntType::new()
-    }
-
-    fn canonical(&self) -> Self::CanonicalType {
-        *self
-    }
-
-    fn source_location(&self) -> SourceLocation {
-        SourceLocation::builtin()
-    }
-
-    fn type_enum(&self) -> TypeEnum {
-        TypeEnum::EnumType(*self)
-    }
-
-    fn from_canonical_type(t: Self::CanonicalType) -> Self {
-        t
-    }
-
-    fn as_dyn_canonical_type_impl(this: &Self) -> Option<&dyn DynCanonicalType> {
-        Some(this)
-    }
-}
-
-impl Connect<Self> for DynEnumType {}
-
-pub struct NoBuilder;
-
-impl EnumType for DynEnumType {
-    type Builder = NoBuilder;
-
+impl EnumType for Enum {
     fn match_activate_scope(
         v: Self::MatchVariantAndInactiveScope,
     ) -> (Self::MatchVariant, Self::MatchActiveScope) {
         let (expr, scope) = v.0.activate();
-        (expr.variant_type().ty.map(|_| expr.to_expr()), scope)
+        (expr.variant_type().map(|_| expr.to_expr()), scope)
     }
-
-    fn builder() -> Self::Builder {
-        NoBuilder
-    }
-
-    fn variants(&self) -> Interned<[VariantType<Interned<dyn DynCanonicalType>>]> {
+    fn variants(&self) -> Interned<[EnumVariant]> {
         self.0.variants
     }
+}
 
-    fn variants_hint() -> VariantsHint {
-        VariantsHint {
-            known_variants: [][..].intern(),
-            more_variants: true,
-        }
+impl Type for Enum {
+    type MaskType = Bool;
+    type MatchVariant = Option<Expr<CanonicalType>>;
+    type MatchActiveScope = Scope;
+    type MatchVariantAndInactiveScope = EnumMatchVariantAndInactiveScope<Self>;
+    type MatchVariantsIter = EnumMatchVariantsIter<Self>;
+
+    fn match_variants(
+        this: Expr<Self>,
+        module_builder: &mut ModuleBuilder<NormalModule>,
+        source_location: crate::source_location::SourceLocation,
+    ) -> Self::MatchVariantsIter {
+        module_builder.enum_match_variants_helper(this, source_location)
+    }
+
+    fn mask_type(&self) -> Self::MaskType {
+        Bool
+    }
+
+    fn canonical(&self) -> CanonicalType {
+        CanonicalType::Enum(*self)
+    }
+
+    #[track_caller]
+    fn from_canonical(canonical_type: CanonicalType) -> Self {
+        let CanonicalType::Enum(retval) = canonical_type else {
+            panic!("expected enum");
+        };
+        retval
+    }
+    fn source_location() -> SourceLocation {
+        SourceLocation::builtin()
     }
 }
 
-impl CanonicalType for DynEnumType {
-    const CANONICAL_TYPE_KIND: CanonicalTypeKind = CanonicalTypeKind::EnumType;
-}
-
-impl ToExpr for DynEnum {
-    type Type = DynEnumType;
-
-    fn ty(&self) -> Self::Type {
-        self.ty
-    }
-
-    fn to_expr(&self) -> Expr<<Self::Type as Type>::Value> {
-        Expr::from_value(self)
-    }
-}
-
-impl Value for DynEnum {
-    fn to_canonical(&self) -> <Self::Type as Type>::CanonicalValue {
-        self.clone()
-    }
-    fn to_bits_impl(this: &Self) -> Interned<BitSlice> {
-        this.ty
-            .variant_to_bits(this.variant_index, this.variant_value.as_ref())
-            .unwrap()
-    }
-}
-
-impl EnumValue for DynEnum {}
-
-impl CanonicalValue for DynEnum {
-    fn value_enum_impl(this: &Self) -> ValueEnum {
-        ValueEnum::Enum(this.clone())
-    }
-    fn to_bits_impl(this: &Self) -> Interned<BitSlice> {
-        this.ty
-            .variant_to_bits(this.variant_index, this.variant_value.as_ref())
-            .unwrap()
-    }
-}
-
-mod impl_option {
-    #[allow(dead_code)]
-    #[derive(crate::ty::Value)]
-    #[hdl(target(std::option::Option), connect_inexact, outline_generated)]
-    pub enum Option<T> {
-        None,
-        Some(T),
-    }
+#[hdl]
+pub enum HdlOption<T: Type> {
+    None,
+    Some(T),
 }

crates/fayalite/src/lib.rs

@@ -12,7 +12,6 @@ extern crate self as fayalite;
 pub use std as __std;
 
 #[doc(inline)]
-#[doc(alias = "hdl")]
 /// The `#[hdl_module]` attribute is applied to a Rust function so that that function creates
 /// a [`Module`][`::fayalite::module::Module`] when called.
 /// In the function body it will implicitly create a
@@ -21,25 +20,82 @@ pub use std as __std;
 /// See [Fayalite Modules][crate::_docs::modules]
 pub use fayalite_proc_macros::hdl_module;
 
+#[doc(inline)]
+pub use fayalite_proc_macros::hdl;
+
 #[cfg(feature = "unstable-doc")]
 pub mod _docs;
 
-pub mod annotations;
+// FIXME: finish
+//pub mod annotations;
 pub mod array;
 pub mod bundle;
-pub mod cli;
-pub mod clock;
+//pub mod cli;
+//pub mod clock;
 pub mod enum_;
 pub mod expr;
-pub mod firrtl;
+//pub mod firrtl;
 pub mod int;
 pub mod intern;
-pub mod memory;
-pub mod module;
-pub mod reg;
-pub mod reset;
+//pub mod memory;
+//pub mod module;
+//pub mod reg;
+//pub mod reset;
 pub mod source_location;
 pub mod ty;
 pub mod util;
-pub mod valueless;
-pub mod wire;
+//pub mod valueless;
+//pub mod wire;
+
+// FIXME: switch to real module mod
+pub mod module {
+    use crate::{
+        enum_::{EnumMatchVariantsIter, EnumType},
+        expr::{ops::VariantAccess, Expr},
+        intern::Interned,
+        source_location::SourceLocation,
+    };
+    use std::marker::PhantomData;
+
+    pub struct NormalModule;
+
+    pub struct ModuleBuilder<ModuleKind>(PhantomData<ModuleKind>);
+
+    impl ModuleBuilder<NormalModule> {
+        pub fn enum_match_variants_helper<Enum: EnumType>(
+            &mut self,
+            _base: Expr<Enum>,
+            _source_location: SourceLocation,
+        ) -> EnumMatchVariantsIter<Enum> {
+            todo!()
+        }
+    }
+
+    pub struct Scope(());
+
+    pub(crate) struct EnumMatchVariantAndInactiveScopeImpl<T: EnumType> {
+        variant_access: Interned<VariantAccess>,
+        _phantom: PhantomData<T>,
+    }
+
+    impl<T: EnumType> EnumMatchVariantAndInactiveScopeImpl<T> {
+        pub(crate) fn activate(self) -> (Interned<VariantAccess>, Scope) {
+            (self.variant_access, Scope(()))
+        }
+        pub(crate) fn variant_access(&self) -> Interned<VariantAccess> {
+            self.variant_access
+        }
+    }
+
+    #[derive(Clone)]
+    pub(crate) struct EnumMatchVariantsIterImpl<T>(PhantomData<T>);
+
+    impl<T: EnumType> EnumMatchVariantsIterImpl<T> {
+        pub(crate) fn for_variant_index(
+            &self,
+            _variant_index: usize,
+        ) -> EnumMatchVariantAndInactiveScopeImpl<T> {
+            todo!()
+        }
+    }
+}

crates/fayalite/src/util.rs

@@ -3,10 +3,13 @@
 
 mod const_bool;
 mod const_cmp;
+mod const_usize;
 mod misc;
 
 #[doc(inline)]
 pub use const_bool::{ConstBool, ConstBoolDispatch, ConstBoolDispatchTag, GenericConstBool};
+#[doc(inline)]
+pub use const_usize::{ConstUsize, GenericConstUsize};
 
 #[doc(inline)]
 pub use const_cmp::{

crates/fayalite/src/util/const_usize.rs

@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: LGPL-3.0-or-later
+// See Notices.txt for copyright information
+use std::{fmt::Debug, hash::Hash};
+
+mod sealed {
+    pub trait Sealed {}
+}
+
+/// the only implementation is `ConstUsize<Self::VALUE>`
+pub trait GenericConstUsize:
+    sealed::Sealed + Copy + Ord + Hash + Default + Debug + 'static + Send + Sync
+{
+    const VALUE: usize;
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
+pub struct ConstUsize<const VALUE: usize>;
+
+impl<const VALUE: usize> Debug for ConstUsize<VALUE> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_tuple("ConstUsize").field(&Self::VALUE).finish()
+    }
+}
+
+impl<const VALUE: usize> sealed::Sealed for ConstUsize<VALUE> {}
+
+impl<const VALUE: usize> GenericConstUsize for ConstUsize<VALUE> {
+    const VALUE: usize = VALUE;
+}

crates/fayalite/tests/value_derive.rs

@@ -1,32 +1,21 @@
 // SPDX-License-Identifier: LGPL-3.0-or-later
 // See Notices.txt for copyright information
-use fayalite::{
-    int::UInt,
-    ty::{StaticValue, Value},
-};
+use fayalite::{hdl, int::UInt, ty::Type};
 
-#[derive(Value, Clone, Hash, PartialEq, Eq, Debug)]
 #[hdl(outline_generated)]
-pub struct S<T> {
+pub struct S<T: Type> {
     pub a: T,
     b: UInt<3>,
 }
 
-#[derive(Value, Clone, Hash, PartialEq, Eq, Debug)]
 #[hdl(outline_generated)]
-pub enum E<T> {
+pub enum E<T: Type> {
     A,
-    B {},
-    C(),
-    D(UInt<3>),
-    E { a: UInt<3> },
-    F(UInt<3>, UInt<3>),
-    G(T),
-    H(T, UInt<1>),
+    B(UInt<3>),
+    C(T),
 }
 
-#[derive(Value, Clone, Hash, PartialEq, Eq, Debug)]
-#[hdl(outline_generated, static, where(T: StaticValue))]
-pub struct S2<T> {
+#[hdl(outline_generated)]
+pub struct S2<T: Type> {
     pub v: E<T>,
 }