Introduce Type::Signature to the AST

compiler/ast/src/types/type_.rs

@@ -40,6 +40,8 @@ pub enum Type {
     Mapping(MappingType),
     /// The `scalar` type.
     Scalar,
+    /// The `signature` type.
+    Signature,
     /// The `string` type.
     String,
     /// A static tuple of at least one type.
@@ -64,6 +66,7 @@ impl Type {
             | (Type::Field, Type::Field)
             | (Type::Group, Type::Group)
             | (Type::Scalar, Type::Scalar)
+            | (Type::Signature, Type::Signature)
             | (Type::String, Type::String)
             | (Type::Unit, Type::Unit) => true,
             (Type::Integer(left), Type::Integer(right)) => left.eq(right),
@@ -90,6 +93,7 @@ impl fmt::Display for Type {
             Type::Integer(ref integer_type) => write!(f, "{integer_type}"),
             Type::Mapping(ref mapping_type) => write!(f, "{mapping_type}"),
             Type::Scalar => write!(f, "scalar"),
+            Type::Signature => write!(f, "signature"),
             Type::String => write!(f, "string"),
             Type::Tuple(ref tuple) => write!(f, "{tuple}"),
             Type::Unit => write!(f, "()"),

compiler/passes/src/code_generation/visit_type.rs

@@ -26,6 +26,7 @@ impl<'a> CodeGenerator<'a> {
             | Type::Field
             | Type::Group
             | Type::Scalar
+            | Type::Signature
             | Type::String
             | Type::Integer(..) => format!("{input}"),
             Type::Identifier(ident) => format!("{ident}"),

compiler/span/src/symbol.rs

@@ -208,6 +208,7 @@ symbols! {
     i128,
     record,
     scalar,
+    signature,
     string,
     Struct: "struct",
     u8,