Fixes #5293: Generate IsAbility constraint for ability sets

parser-typechecker/src/Unison/KindInference/Generate.hs

@@ -101,7 +101,7 @@ typeConstraintTree resultVar [email protected] {annotation, out} = do
         restConstraints <- typeConstraintTree resultVar b
         pure $ Node [effConstraints, restConstraints]
       Type.Effects effs -> do
-        Node <$> for effs \eff -> do
+        ParentConstraint (IsAbility resultVar (Provenance EffectsList annotation)) . Node <$> for effs \eff -> do
           effKind <- freshVar eff
           effConstraints <- typeConstraintTree effKind eff
           pure $ ParentConstraint (IsAbility effKind (Provenance EffectsList $ ABT.annotation eff)) effConstraints

unison-src/tests/type-application.u

@@ -3,6 +3,7 @@ structural ability Foo where
   foo : {Foo} Nat
 
 structural type Wrap a = Wrap Nat
+structural type C = C (Wrap {}) -- constrain Wrap kind
 
 blah : Wrap {Foo} -> Nat
 blah = cases

unison-src/transcripts/fix3196.md

@@ -15,6 +15,9 @@ structural type W es = W
 unique ability Zoot where
   zoot : ()
 
+-- here only to put a kind constraint on W
+structural type C = C (W {})
+
 woot : W {g} -> '{g, Zoot} a ->{Zoot} a
 woot w a = todo ()
 

unison-src/transcripts/fix3196.output.md

@@ -10,6 +10,9 @@ structural type W es = W
 unique ability Zoot where
   zoot : ()
 
+-- here only to put a kind constraint on W
+structural type C = C (W {})
+
 woot : W {g} -> '{g, Zoot} a ->{Zoot} a
 woot w a = todo ()
 
@@ -36,6 +39,7 @@ w2 = cases W -> W
 
     ⍟ These new definitions are ok to `add`:
 
+      structural type C
       structural type W es
       ability Zoot
       ex   : '{Zoot} r
@@ -46,7 +50,7 @@ w2 = cases W -> W
   Now evaluating any watch expressions (lines starting with
   `>`)... Ctrl+C cancels.
 
-    19 | > w2 w1
+    22 | > w2 w1
            ⧩
            W