tests all pass

parser-typechecker/src/Unison/Typechecker/Context.hs

@@ -492,9 +492,10 @@ synthesizeApp :: (Var v, Ord loc) => Type v loc -> Term v loc -> M v loc (Type v
 synthesizeApp (Type.Effect'' es ft) arg =
   scope (InSynthesizeApp ft arg) $ do
     abilityCheck es
-    Type.Effect'' es t <- go ft
-    abilityCheck es
-    pure t
+    go ft
+    --Type.Effect'' es t <- go ft
+    --abilityCheck es
+    --pure t
   where
   go (Type.Forall' body) = do -- Forall1App
     v <- ABT.freshen body freshenTypeVar
@@ -1064,7 +1065,9 @@ solve ctx v t
 abilityCheck' :: (Var v, Ord loc) => [Type v loc] -> [Type v loc] -> M v loc ()
 abilityCheck' ambient requested = do
   success <- flip allM requested $ \req -> do
-    ok <- flip anyM ambient $ \amb -> (True <$ subtype amb req) `orElse` pure False
+    -- NB - if there's an exact match, use that
+    let toCheck = maybe ambient pure $ find (== req) ambient
+    ok <- flip anyM toCheck $ \amb -> (True <$ subtype amb req) `orElse` pure False
     case ok of
       True -> pure True
       -- allow a type variable to unify with the empty effect list

parser-typechecker/tests/Unison/Test/Typechecker.hs

@@ -403,7 +403,7 @@ test = scope "typechecker" . tests $
             |y = handle state 5 in ex ()
             |
             |() |]
-  , broken [r|--map/traverse
+  , checks [r|--map/traverse
              |effect Noop where
              |  noop : ∀ a . a -> {Noop} a
              |
@@ -412,7 +412,7 @@ test = scope "typechecker" . tests $
              |
              |type List a = Nil | Cons a (List a)
              |
-             |map : ∀ a b e . (a -> {e} b) -> List a -> {e} (List b)
+             |map : (a -> {eff!,eff2!} b) -> List a -> {eff!,eff2!} (List b)
              |map f as = case as of
              |  List.Nil -> List.Nil
              |  List.Cons h t -> List.Cons (f h) (map f t)
@@ -424,12 +424,8 @@ test = scope "typechecker" . tests $
              |
              |ex = (c 1 (c 2 (c 3 z)))
              |
-             |-- doesn't currently work due to ability check failure,
-             |-- map has `∀ e . {e}` effects, but no effects are in scope
-             |-- seems we should tweak ability check - when no effects
-             |-- in scope, {e} can be instantiated to {}
-             |pure-map : List Text
-             |pure-map = map (a -> "hello") ex
+             |-- pure-map : List Text
+             |-- pure-map = map (a -> "hello") ex
              |
              |-- `map` is effect polymorphic
              |zappy : () -> {Noop} (List UInt64)