feat!: CustomConst is not restricted to being CustomType (#878)

quantinuum-hugr/src/extension/prelude.rs

@@ -191,8 +191,8 @@ impl CustomConst for ConstUsize {
         ExtensionSet::singleton(&PRELUDE_ID)
     }
 
-    fn custom_type(&self) -> CustomType {
-        USIZE_CUSTOM_T
+    fn get_type(&self) -> Type {
+        USIZE_T
     }
 }
 
@@ -228,8 +228,8 @@ impl CustomConst for ConstError {
     fn extension_reqs(&self) -> ExtensionSet {
         ExtensionSet::singleton(&PRELUDE_ID)
     }
-    fn custom_type(&self) -> CustomType {
-        ERROR_CUSTOM_TYPE
+    fn get_type(&self) -> Type {
+        ERROR_TYPE
     }
 }
 

quantinuum-hugr/src/ops/constant.rs

@@ -129,7 +129,7 @@ where
     T: CustomConst,
 {
     fn from(value: T) -> Self {
-        let typ = Type::new_extension(value.custom_type());
+        let typ = value.get_type();
         Const {
             value: Value::custom(value),
             typ,
@@ -263,9 +263,8 @@ mod test {
         assert_matches!(classic_t.least_upper_bound(), TypeBound::Eq);
         classic_t.check_type(&val).unwrap();
 
-        let typ_qb = CustomType::new("mytype", vec![], ex_id, TypeBound::Eq);
-        let t = Type::new_extension(typ_qb.clone());
-        assert_matches!(t.check_type(&val),
+        let typ_qb: Type = CustomType::new("mytype", vec![], ex_id, TypeBound::Eq).into();
+        assert_matches!(typ_qb.check_type(&val),
             Err(ConstTypeError::CustomCheckFail(CustomCheckFailure::TypeMismatch{expected, found})) => expected == typ_int && found == typ_qb);
 
         assert_eq!(val, val);

quantinuum-hugr/src/std_extensions/arithmetic/float_types.rs

@@ -56,8 +56,8 @@ impl CustomConst for ConstF64 {
         format!("f64({})", self.value).into()
     }
 
-    fn custom_type(&self) -> CustomType {
-        FLOAT64_CUSTOM_TYPE
+    fn get_type(&self) -> Type {
+        FLOAT64_TYPE
     }
 
     fn equal_consts(&self, other: &dyn CustomConst) -> bool {

quantinuum-hugr/src/std_extensions/arithmetic/int_types.rs

@@ -157,8 +157,8 @@ impl CustomConst for ConstIntU {
         ExtensionSet::singleton(&EXTENSION_ID)
     }
 
-    fn custom_type(&self) -> CustomType {
-        int_custom_type(type_arg(self.log_width))
+    fn get_type(&self) -> Type {
+        int_type(type_arg(self.log_width))
     }
 }
 
@@ -175,8 +175,8 @@ impl CustomConst for ConstIntS {
         ExtensionSet::singleton(&EXTENSION_ID)
     }
 
-    fn custom_type(&self) -> CustomType {
-        int_custom_type(type_arg(self.log_width))
+    fn get_type(&self) -> Type {
+        int_type(type_arg(self.log_width))
     }
 }
 

quantinuum-hugr/src/std_extensions/collections.rs

@@ -45,6 +45,11 @@ impl ListValue {
     pub fn new_empty(typ: Type) -> Self {
         Self(vec![], typ)
     }
+
+    /// Returns the type of the `[ListValue]` as a `[CustomType]`.`
+    pub fn custom_type(&self) -> CustomType {
+        list_custom_type(self.1.clone())
+    }
 }
 
 #[typetag::serde]
@@ -53,11 +58,8 @@ impl CustomConst for ListValue {
         SmolStr::new_inline("list")
     }
 
-    fn custom_type(&self) -> CustomType {
-        let list_type_def = EXTENSION.get_type(&LIST_TYPENAME).unwrap();
-        list_type_def
-            .instantiate(vec![Into::<TypeArg>::into(self.1.clone())])
-            .unwrap()
+    fn get_type(&self) -> Type {
+        self.custom_type().into()
     }
 
     fn validate(&self) -> Result<(), CustomCheckFailure> {
@@ -176,15 +178,18 @@ lazy_static! {
     pub static ref EXTENSION: Extension = extension();
 }
 
-/// Get the type of a list of `elem_type`
+/// Get the type of a list of `elem_type` as a `CustomType`.
+pub fn list_custom_type(elem_type: Type) -> CustomType {
+    EXTENSION
+        .get_type(&LIST_TYPENAME)
+        .unwrap()
+        .instantiate(vec![TypeArg::Type { ty: elem_type }])
+        .unwrap()
+}
+
+/// Get the `Type` of a list of `elem_type`.
 pub fn list_type(elem_type: Type) -> Type {
-    Type::new_extension(
-        EXTENSION
-            .get_type(&LIST_TYPENAME)
-            .unwrap()
-            .instantiate(vec![TypeArg::Type { ty: elem_type }])
-            .unwrap(),
-    )
+    list_custom_type(elem_type).into()
 }
 
 fn list_and_elem_type_vars(list_type_def: &TypeDef) -> (Type, Type) {

quantinuum-hugr/src/types/check.rs

@@ -19,7 +19,7 @@ pub enum CustomCheckFailure {
         /// The expected custom type.
         expected: CustomType,
         /// The custom type found when checking.
-        found: CustomType,
+        found: Type,
     },
     /// Any other message
     #[error("{0}")]
@@ -107,8 +107,8 @@ impl Type {
     pub fn check_type(&self, val: &Value) -> Result<(), ConstTypeError> {
         match (&self.0, val) {
             (TypeEnum::Extension(expected), Value::Extension { c: (e_val,) }) => {
-                let found = e_val.custom_type();
-                if found == *expected {
+                let found = e_val.get_type();
+                if found == expected.clone().into() {
                     Ok(e_val.validate()?)
                 } else {
                     Err(CustomCheckFailure::TypeMismatch {

quantinuum-hugr/src/types/custom.rs

@@ -5,11 +5,11 @@ use std::fmt::{self, Display};
 
 use crate::extension::{ExtensionId, ExtensionRegistry, SignatureError, TypeDef};
 
-use super::TypeName;
 use super::{
     type_param::{TypeArg, TypeParam},
     Substitution, TypeBound,
 };
+use super::{Type, TypeName};
 
 /// An opaque type element. Contains the unique identifier of its definition.
 #[derive(Debug, PartialEq, Eq, Clone, serde::Serialize, serde::Deserialize)]
@@ -131,3 +131,9 @@ impl Display for CustomType {
         }
     }
 }
+
+impl From<CustomType> for Type {
+    fn from(value: CustomType) -> Self {
+        Self::new_extension(value)
+    }
+}

quantinuum-hugr/src/values.rs

@@ -14,15 +14,14 @@ use crate::macros::impl_box_clone;
 
 use crate::{Hugr, HugrView};
 
-use crate::types::{CustomCheckFailure, CustomType};
+use crate::types::{CustomCheckFailure, Type};
 
 /// A value that can be stored as a static constant. Representing core types and
 /// extension types.
 #[derive(Clone, Debug, PartialEq, serde::Serialize, serde::Deserialize)]
 #[serde(tag = "v")]
 pub enum Value {
-    /// An extension constant value, that can check it is of a given [CustomType].
-    ///
+    /// An extension constant value.
     // Note: the extra level of tupling is to avoid https://github.com/rust-lang/rust/issues/78808
     Extension {
         #[allow(missing_docs)]
@@ -139,10 +138,12 @@ impl<T: CustomConst> From<T> for Value {
     }
 }
 
-/// Constant value for opaque [`CustomType`]s.
+/// Constant value for opaque `[CustomType]`s.
 ///
 /// When implementing this trait, include the `#[typetag::serde]` attribute to
 /// enable serialization.
+///
+/// [CustomType]: crate::types::CustomType
 #[typetag::serde(tag = "c")]
 pub trait CustomConst:
     Send + Sync + std::fmt::Debug + CustomConstBoxClone + Any + Downcast
@@ -170,7 +171,7 @@ pub trait CustomConst:
     }
 
     /// report the type
-    fn custom_type(&self) -> CustomType;
+    fn get_type(&self) -> Type;
 }
 
 /// Const equality for types that have PartialEq
@@ -191,19 +192,22 @@ impl_box_clone!(CustomConst, CustomConstBoxClone);
 #[derive(Debug, Clone, PartialEq, serde::Serialize, serde::Deserialize)]
 /// A value stored as a serialized blob that can report its own type.
 pub struct CustomSerialized {
-    typ: CustomType,
+    typ: Type,
     value: serde_yaml::Value,
     extensions: ExtensionSet,
 }
 
 impl CustomSerialized {
     /// Creates a new [`CustomSerialized`].
-    pub fn new(typ: CustomType, value: serde_yaml::Value, exts: impl Into<ExtensionSet>) -> Self {
-        let extensions = exts.into();
+    pub fn new(
+        typ: impl Into<Type>,
+        value: serde_yaml::Value,
+        exts: impl Into<ExtensionSet>,
+    ) -> Self {
         Self {
-            typ,
+            typ: typ.into(),
             value,
-            extensions,
+            extensions: exts.into(),
         }
     }
 
@@ -226,7 +230,7 @@ impl CustomConst for CustomSerialized {
     fn extension_reqs(&self) -> ExtensionSet {
         self.extensions.clone()
     }
-    fn custom_type(&self) -> CustomType {
+    fn get_type(&self) -> Type {
         self.typ.clone()
     }
 }
@@ -244,9 +248,9 @@ pub(crate) mod test {
     use super::*;
     use crate::builder::test::simple_dfg_hugr;
     use crate::ops::Const;
-    use crate::std_extensions::arithmetic::float_types::{self, FLOAT64_CUSTOM_TYPE};
+    use crate::std_extensions::arithmetic::float_types::{self, FLOAT64_TYPE};
     use crate::type_row;
-    use crate::types::{FunctionType, Type};
+    use crate::types::{CustomType, FunctionType, Type};
 
     #[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
 
@@ -262,14 +266,14 @@ pub(crate) mod test {
             ExtensionSet::singleton(self.0.extension())
         }
 
-        fn custom_type(&self) -> CustomType {
-            self.0.clone()
+        fn get_type(&self) -> Type {
+            self.0.clone().into()
         }
     }
 
     pub(crate) fn serialized_float(f: f64) -> Const {
         CustomSerialized {
-            typ: FLOAT64_CUSTOM_TYPE,
+            typ: FLOAT64_TYPE,
             value: serde_yaml::Value::Number(f.into()),
             extensions: float_types::EXTENSION_ID.into(),
         }