diff --git a/crates/fayalite/src/generics.rs b/crates/fayalite/src/generics.rs
new file mode 100644
index 0000000..ac5d88a
--- /dev/null
+++ b/crates/fayalite/src/generics.rs
@@ -0,0 +1,368 @@
+use crate::{
+    intern::{Intern, Interned},
+    source_location::SourceLocation,
+    ty::{DynCanonicalType, Type, Value},
+    util::DebugAsDisplay,
+};
+use std::{fmt, hash::Hash};
+
+mod sealed {
+    pub trait GenericArgsSealed {}
+    pub trait ToGenericArgSealed {}
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
+pub struct GenericParamName {
+    pub name: Interned<str>,
+    pub source_location: SourceLocation,
+}
+
+impl GenericParamName {
+    #[track_caller]
+    pub fn new(name: &str) -> Self {
+        Self::new_with_loc(name, SourceLocation::caller())
+    }
+    pub fn new_with_loc(name: &str, source_location: SourceLocation) -> Self {
+        let name = name.intern();
+        Self {
+            name,
+            source_location,
+        }
+    }
+}
+
+impl fmt::Debug for GenericParamName {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.name.fmt(f)
+    }
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
+pub struct TypeParam {
+    pub name: GenericParamName,
+    pub default: Option<fn(earlier_args: &[GenericArg]) -> TypeArg>,
+}
+
+impl fmt::Debug for TypeParam {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("TypeParam")
+            .field("name", &self.name)
+            .field("default", &self.default.map(|_| DebugAsDisplay("_")))
+            .finish()
+    }
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
+pub struct ConstParam {
+    pub name: GenericParamName,
+    pub default: Option<fn(earlier_args: &[GenericArg]) -> ConstArg>,
+}
+
+impl fmt::Debug for ConstParam {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("ConstParam")
+            .field("name", &self.name)
+            .field("default", &self.default.map(|_| DebugAsDisplay("_")))
+            .finish()
+    }
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
+pub enum GenericParam {
+    Type(TypeParam),
+    Const(ConstParam),
+}
+
+impl fmt::Debug for GenericParam {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Type(v) => v.fmt(f),
+            Self::Const(v) => v.fmt(f),
+        }
+    }
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
+pub struct TypeArg<T: Type = Interned<dyn DynCanonicalType>> {
+    pub ty: T,
+}
+
+impl<T: Type> TypeArg<T> {
+    pub fn canonical(&self) -> TypeArg {
+        TypeArg {
+            ty: self.ty.canonical_dyn(),
+        }
+    }
+}
+
+impl<T: Type> sealed::ToGenericArgSealed for T {}
+
+impl<T: Type> ToGenericArg for T {
+    fn to_generic_arg(this: &Self) -> GenericArg {
+        GenericArg::Type(TypeArg {
+            ty: this.canonical_dyn(),
+        })
+    }
+}
+
+impl<T: Type> sealed::ToGenericArgSealed for TypeArg<T> {}
+
+impl<T: Type> ToGenericArg for TypeArg<T> {
+    fn to_generic_arg(this: &Self) -> GenericArg {
+        GenericArg::Type(this.canonical())
+    }
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
+pub struct ConstArg {
+    pub value: usize,
+}
+
+impl sealed::ToGenericArgSealed for usize {}
+
+impl ToGenericArg for usize {
+    fn to_generic_arg(this: &Self) -> GenericArg {
+        GenericArg::Const(ConstArg { value: *this })
+    }
+}
+
+impl sealed::ToGenericArgSealed for ConstArg {}
+
+impl ToGenericArg for ConstArg {
+    fn to_generic_arg(this: &Self) -> GenericArg {
+        GenericArg::Const(*this)
+    }
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, Default)]
+pub struct DefaultArg;
+
+impl sealed::ToGenericArgSealed for DefaultArg {}
+
+impl ToGenericArg for DefaultArg {
+    fn to_generic_arg(this: &Self) -> GenericArg {
+        GenericArg::Default(*this)
+    }
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
+pub enum GenericArg<T: Type = Interned<dyn DynCanonicalType>> {
+    Type(TypeArg<T>),
+    Const(ConstArg),
+    Default(DefaultArg),
+}
+
+#[derive(Copy, Clone, Debug)]
+pub struct NotATypeArg;
+
+impl fmt::Display for NotATypeArg {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str("not a type argument")
+    }
+}
+
+impl std::error::Error for NotATypeArg {}
+
+#[derive(Copy, Clone, Debug)]
+pub struct NotAConstArg;
+
+impl fmt::Display for NotAConstArg {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str("not a const argument")
+    }
+}
+
+impl std::error::Error for NotAConstArg {}
+
+impl<T: Type> GenericArg<T> {
+    pub fn canonical(&self) -> GenericArg {
+        match self {
+            GenericArg::Type(v) => GenericArg::Type(v.canonical()),
+            GenericArg::Const(v) => GenericArg::Const(*v),
+            GenericArg::Default(v) => GenericArg::Default(*v),
+        }
+    }
+    pub fn ty(self) -> Result<T, NotATypeArg> {
+        match self {
+            GenericArg::Type(TypeArg { ty }) => Ok(ty),
+            GenericArg::Const(_) | GenericArg::Default(_) => Err(NotATypeArg),
+        }
+    }
+    pub fn const_(self) -> Result<usize, NotAConstArg> {
+        match self {
+            GenericArg::Const(ConstArg { value }) => Ok(value),
+            GenericArg::Type(_) | GenericArg::Default(_) => Err(NotAConstArg),
+        }
+    }
+}
+
+impl<T: Type> fmt::Debug for GenericArg<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Type(v) => v.fmt(f),
+            Self::Const(v) => v.fmt(f),
+            Self::Default(v) => v.fmt(f),
+        }
+    }
+}
+
+impl<T: Type> sealed::ToGenericArgSealed for GenericArg<T> {}
+
+impl<T: Type> ToGenericArg for GenericArg<T> {
+    fn to_generic_arg(this: &Self) -> GenericArg {
+        this.canonical()
+    }
+}
+
+pub trait ToGenericArg: sealed::ToGenericArgSealed {
+    fn to_generic_arg(this: &Self) -> GenericArg;
+}
+
+pub trait GenericArgs: sealed::GenericArgsSealed {
+    fn generic_args(this: &Self) -> Vec<GenericArg>;
+}
+
+impl<T: GenericArgs + ?Sized + Send + Sync + 'static> sealed::GenericArgsSealed for Interned<T> {}
+
+impl<T: GenericArgs + ?Sized + Send + Sync + 'static> GenericArgs for Interned<T> {
+    fn generic_args(this: &Self) -> Vec<GenericArg> {
+        T::generic_args(this)
+    }
+}
+
+impl<T: GenericArgs + ?Sized> sealed::GenericArgsSealed for Box<T> {}
+
+impl<T: GenericArgs + ?Sized> GenericArgs for Box<T> {
+    fn generic_args(this: &Self) -> Vec<GenericArg> {
+        T::generic_args(this)
+    }
+}
+
+impl<T: GenericArgs + ?Sized> sealed::GenericArgsSealed for &'_ T {}
+
+impl<T: GenericArgs + ?Sized> GenericArgs for &'_ T {
+    fn generic_args(this: &Self) -> Vec<GenericArg> {
+        T::generic_args(this)
+    }
+}
+
+impl<T: GenericArgs + ?Sized> sealed::GenericArgsSealed for &'_ mut T {}
+
+impl<T: GenericArgs + ?Sized> GenericArgs for &'_ mut T {
+    fn generic_args(this: &Self) -> Vec<GenericArg> {
+        T::generic_args(this)
+    }
+}
+
+impl<T: ToGenericArg> sealed::GenericArgsSealed for [T] {}
+
+impl<T: ToGenericArg> GenericArgs for [T] {
+    fn generic_args(this: &Self) -> Vec<GenericArg> {
+        Vec::from_iter(this.iter().map(ToGenericArg::to_generic_arg))
+    }
+}
+
+impl<T: ToGenericArg> sealed::GenericArgsSealed for Vec<T> {}
+
+impl<T: ToGenericArg> GenericArgs for Vec<T> {
+    fn generic_args(this: &Self) -> Vec<GenericArg> {
+        Vec::from_iter(this.iter().map(ToGenericArg::to_generic_arg))
+    }
+}
+
+impl<T: ToGenericArg, const N: usize> sealed::GenericArgsSealed for [T; N] {}
+
+impl<T: ToGenericArg, const N: usize> GenericArgs for [T; N] {
+    fn generic_args(this: &Self) -> Vec<GenericArg> {
+        Vec::from_iter(this.iter().map(ToGenericArg::to_generic_arg))
+    }
+}
+
+macro_rules! impl_generic_args_for_tuples {
+    ($($v:ident: $T:ident),*) => {
+        impl<$($T: ToGenericArg,)*> sealed::GenericArgsSealed for ($($T,)*) {}
+
+        impl<$($T: ToGenericArg,)*> GenericArgs for ($($T,)*) {
+            fn generic_args(this: &Self) -> Vec<GenericArg> {
+                let ($($v,)*) = this;
+                vec![$($T::to_generic_arg($v),)*]
+            }
+        }
+    };
+}
+
+impl_generic_args_for_tuples!();
+impl_generic_args_for_tuples!(a: A);
+impl_generic_args_for_tuples!(a: A, b: B);
+impl_generic_args_for_tuples!(a: A, b: B, c: C);
+impl_generic_args_for_tuples!(a: A, b: B, c: C, d: D);
+impl_generic_args_for_tuples!(a: A, b: B, c: C, d: D, e: E);
+impl_generic_args_for_tuples!(a: A, b: B, c: C, d: D, e: E, f: F);
+impl_generic_args_for_tuples!(a: A, b: B, c: C, d: D, e: E, f: F, g: G);
+impl_generic_args_for_tuples!(a: A, b: B, c: C, d: D, e: E, f: F, g: G, h: H);
+impl_generic_args_for_tuples!(a: A, b: B, c: C, d: D, e: E, f: F, g: G, h: H, i: I);
+impl_generic_args_for_tuples!(a: A, b: B, c: C, d: D, e: E, f: F, g: G, h: H, i: I, j: J);
+impl_generic_args_for_tuples!(a: A, b: B, c: C, d: D, e: E, f: F, g: G, h: H, i: I, j: J, k: K);
+impl_generic_args_for_tuples!(a: A, b: B, c: C, d: D, e: E, f: F, g: G, h: H, i: I, j: J, k: K, l: L);
+
+#[track_caller]
+pub fn canonical_generic_args(
+    mut generic_args: Vec<GenericArg>,
+    generic_params: &[GenericParam],
+) -> Interned<[GenericArg]> {
+    assert!(generic_params.len() >= generic_args.len());
+    for (i, generic_param) in generic_params.iter().enumerate() {
+        match generic_args.get(i) {
+            Some(GenericArg::Default(DefaultArg)) | None => {}
+            Some(GenericArg::Type(_)) | Some(GenericArg::Const(_)) => continue,
+        }
+        let generic_arg = match generic_param {
+            GenericParam::Type(TypeParam {
+                name: _,
+                default: Some(default),
+            }) => GenericArg::Type(default(&generic_args[..i])),
+            GenericParam::Type(TypeParam {
+                name:
+                    GenericParamName {
+                        name,
+                        source_location,
+                    },
+                default: None,
+            }) => panic!("Missing type argument for {name} declared here: {source_location}"),
+            GenericParam::Const(ConstParam {
+                name: _,
+                default: Some(default),
+            }) => GenericArg::Const(default(&generic_args[..i])),
+            GenericParam::Const(ConstParam {
+                name:
+                    GenericParamName {
+                        name,
+                        source_location,
+                    },
+                default: None,
+            }) => panic!("Missing const argument for {name} declared here: {source_location}"),
+        };
+        if i == generic_args.len() {
+            generic_args.push(generic_arg)
+        } else {
+            generic_args[i] = generic_arg;
+        }
+    }
+    debug_assert_eq!(generic_params.len(), generic_args.len());
+    Intern::intern_owned(generic_args)
+}
+
+pub trait GenericType {
+    type GenericArgs: GenericArgs;
+    type Type: Type<Value = Self::Value>;
+    type Value: Value<Type = Self::Type>;
+    fn generic_params() -> Interned<[GenericParam]>;
+    #[track_caller]
+    fn canonical_generic_args(generic_args: &Self::GenericArgs) -> Interned<[GenericArg]> {
+        canonical_generic_args(
+            GenericArgs::generic_args(&generic_args),
+            &Self::generic_params(),
+        )
+    }
+    fn ty(generic_args: Interned<[GenericArg]>) -> Self::Type;
+}
diff --git a/crates/fayalite/src/lib.rs b/crates/fayalite/src/lib.rs
index c0a3775..8406a6d 100644
--- a/crates/fayalite/src/lib.rs
+++ b/crates/fayalite/src/lib.rs
@@ -32,6 +32,7 @@ pub mod clock;
 pub mod enum_;
 pub mod expr;
 pub mod firrtl;
+pub mod generics;
 pub mod int;
 pub mod intern;
 pub mod memory;