8a31897 · rowtype-yoga/purescript-native

examples/failing/ConstraintInference.pursnew file+10

compare with golang

unifiedsplit

@@ -0,0 +1,10 @@

1+-- @shouldFailWith NoInstanceFound

2+

3+module Main where

4+

5+import Prelude

6+

7+spin :: forall a b. a -> b

8+spin x = spin x

9+

10+test = show <<< spin

examples/passing/ConstraintInference.pursnew file+7

@@ -0,0 +1,7 @@

1+module Main where

2+

3+import Prelude

4+

5+shout = Control.Monad.Eff.Console.log <<< (<> "!") <<< show

6+

7+main = shout "Done"

src/Language/PureScript/TypeChecker/Types.hs+8

@@ -77,6 +77,14 @@ typesOf moduleName vals = do

77 forM tys $ \(shouldGeneralize, (ident, (val, ty))) -> do

78 -- Replace type class dictionary placeholders with actual dictionaries

79 (val', unsolved) <- replaceTypeClassDictionaries shouldGeneralize moduleName val

80+ let unsolvedTypeVars = nub $ unknownsInType ty

81+ -- Make sure any unsolved type constraints only use type variables which appear

82+ -- unknown in the inferred type.

83+ when shouldGeneralize $

84+ forM_ unsolved $ \(_, (className, classTys)) -> do

85+ let constraintTypeVars = nub $ foldMap unknownsInType classTys

86+ when (any (`notElem` unsolvedTypeVars) constraintTypeVars) $

87+ throwError . errorMessage $ NoInstanceFound className classTys

80 -- Check skolem variables did not escape their scope

88 -- Check skolem variables did not escape their scope

81 skolemEscapeCheck val'

89 skolemEscapeCheck val'

82 -- Check rows do not contain duplicate labels

90 -- Check rows do not contain duplicate labels

src/Language/PureScript/TypeChecker/Unify.hs+1

@@ -23,6 +23,7 @@ module Language.PureScript.TypeChecker.Unify (

23 freshType,

24 solveType,

25 substituteType,

26+ unknownsInType,

26 unifyTypes,

27 unifyTypes,

27 unifyRows,

28 unifyRows,

28 unifiesWith,

29 unifiesWith,