Rework 'is_opaque' to also check for inner types.

Also removed the duplication in infer_assignment and moved the check down.

crates/aiken-lang/src/tipo.rs

@@ -195,10 +195,14 @@ impl Type {
         }
     }
 
-    pub fn is_opaque(&self) -> bool {
+    pub fn is_or_holds_opaque(&self) -> bool {
         match self {
-            Type::App { opaque, .. } => *opaque,
+            Type::Var { tipo, .. } => tipo.borrow().is_or_holds_opaque(),
-            _ => false,
+            Type::App { opaque, args, .. } => {
+                *opaque || args.iter().any(|arg| arg.is_or_holds_opaque())
+            }
+            Type::Tuple { elems, .. } => elems.iter().any(|elem| elem.is_or_holds_opaque()),
+            Type::Fn { .. } => false,
         }
     }
 
@@ -845,6 +849,13 @@ impl TypeVar {
         matches!(self, Self::Unbound { .. })
     }
 
+    pub fn is_or_holds_opaque(&self) -> bool {
+        match self {
+            Self::Link { tipo } => tipo.is_or_holds_opaque(),
+            _ => false,
+        }
+    }
+
     pub fn is_void(&self) -> bool {
         match self {
             Self::Link { tipo } => tipo.is_void(),

crates/aiken-lang/src/tipo/expr.rs

@@ -928,18 +928,13 @@ impl<'a, 'b> ExprTyper<'a, 'b> {
         let mut value_typ = typed_value.tipo();
 
         let value_is_data = value_typ.is_data();
-        let value_is_opaque = value_typ.is_opaque();
 
         // Check that any type annotation is accurate.
-        let pattern = if let Some(ann) = annotation {
+        let ann_typ = if let Some(ann) = annotation {
             let ann_typ = self
                 .type_from_annotation(ann)
                 .map(|t| self.instantiate(t, &mut HashMap::new()))?;
 
-            if kind.is_expect() && (ann_typ.is_opaque() || value_is_opaque) {
-                return Err(Error::ExpectOnOpaqueType { location });
-            }
-
             self.unify(
                 ann_typ.clone(),
                 value_typ.clone(),
@@ -949,13 +944,7 @@ impl<'a, 'b> ExprTyper<'a, 'b> {
 
             value_typ = ann_typ.clone();
 
-            // Ensure the pattern matches the type of the value
+            Some(ann_typ)
-            PatternTyper::new(self.environment, &self.hydrator).unify(
-                untyped_pattern.clone(),
-                value_typ.clone(),
-                Some(ann_typ),
-                kind.is_let(),
-            )?
         } else {
             if value_is_data && !untyped_pattern.is_var() && !untyped_pattern.is_discard() {
                 let ann = Annotation::Constructor {
@@ -976,19 +965,21 @@ impl<'a, 'b> ExprTyper<'a, 'b> {
                 });
             }
 
-            if kind.is_expect() && value_is_opaque {
+            None
-                return Err(Error::ExpectOnOpaqueType { location });
-            }
-
-            // Ensure the pattern matches the type of the value
-            PatternTyper::new(self.environment, &self.hydrator).unify(
-                untyped_pattern.clone(),
-                value_typ.clone(),
-                None,
-                kind.is_let(),
-            )?
         };
 
+        if kind.is_expect() && value_typ.is_or_holds_opaque() {
+            return Err(Error::ExpectOnOpaqueType { location });
+        }
+
+        // Ensure the pattern matches the type of the value
+        let pattern = PatternTyper::new(self.environment, &self.hydrator).unify(
+            untyped_pattern.clone(),
+            value_typ.clone(),
+            ann_typ,
+            kind.is_let(),
+        )?;
+
         // If `expect` is explicitly used, we still check exhaustiveness but instead of returning an
         // error we emit a warning which explains that using `expect` is unnecessary.
         match kind {