iter 22-tidy.6.2: write_fn_def renders forall class constraints

crates/ailang-prose/src/lib.rs

@@ -238,9 +238,11 @@ fn write_fn_def(out: &mut String, fd: &FnDef, level: usize) {
     // `Type::Fn` or a `Type::Forall` wrapping one — in the latter case
     // we render the forall on the line above and then the inner fn
     // signature.
-    let (forall_vars, fn_ty) = match &fd.ty {
-        Type::Forall { vars, constraints: _, body } => (Some(vars.clone()), body.as_ref()),
-        other => (None, other),
+    let (forall_vars, forall_constraints, fn_ty) = match &fd.ty {
+        Type::Forall { vars, constraints, body } => {
+            (Some(vars.clone()), constraints.clone(), body.as_ref())
+        }
+        other => (None, Vec::new(), other),
     };
 
     if let Some(vars) = &forall_vars {
@@ -252,7 +254,19 @@ fn write_fn_def(out: &mut String, fd: &FnDef, level: usize) {
             }
             out.push_str(v);
         }
-        out.push_str(">\n");
+        out.push('>');
+        if !forall_constraints.is_empty() {
+            out.push_str(" where ");
+            for (i, c) in forall_constraints.iter().enumerate() {
+                if i > 0 {
+                    out.push_str(", ");
+                }
+                out.push_str(&c.class);
+                out.push(' ');
+                write_type(out, &c.type_);
+            }
+        }
+        out.push('\n');
     }
 
     indent(out, level);

crates/ailang-prose/tests/snapshot.rs

@@ -81,3 +81,8 @@ fn snapshot_test_22b3_default_e2e() {
 fn snapshot_test_22b2_instance_present() {
     check_snapshot("test_22b2_instance_present");
 }
+
+#[test]
+fn snapshot_test_22b2_constraint_declared_via_superclass() {
+    check_snapshot("test_22b2_constraint_declared_via_superclass");
+}

examples/test_22b2_constraint_declared_via_superclass.prose.txt

@@ -0,0 +1,14 @@
+// module test_22b2_constraint_declared_via_superclass
+
+class Eq a {
+  fn eq(x: a, x1: a) -> Bool
+}
+
+class Ord a extends Eq {
+  fn lt(x: a, x1: a) -> Bool
+}
+
+forall<a> where Ord a
+fn uses_eq_via_ord(x: a, y: a) -> Bool {
+  eq(x, y)
+}