5ed9384 · rowtype-yoga/purescript-native

git.iko.soy/rowtype-yoga/purescript-native

2374: Add error message for ambiguous type variables in inferred contexts (#2410)

* 2374: Add error message for ambiguous type variables in inferred contexts * 2323 add contribution entry. remove Ident from AmbiguousTypeVariables since it's redundant with the enclosing compiler error's ident * 2323 update error message * 2374 multiline error message and print type, not type atom

commit5ed9384bed7a645b500c24550b415f5499bdb0ee authorbbqbaron <osiris1723@gmail.com> dateMon 7 Nov 2016, 09:52 (10 years ago) parent2b04f5a

6 files changed+24−2

compare with golang

unifiedsplit

CONTRIBUTORS.md+1 examples/failing/ConstraintFailure.purs+13 examples/failing/ConstraintInference.purs+1−1 src/Language/PureScript/AST/Declarations.hs+1 src/Language/PureScript/Errors.hs+7 src/Language/PureScript/TypeChecker/Types.hs+1−1

CONTRIBUTORS.md+1

@@ -83,6 +83,7 @@ This file lists the contributors to the PureScript compiler project, and the ter

8383- [@vkorablin](https://github.com/vkorablin) (Vladimir Korablin) - My existing contributions and all future contributions until further notice are Copyright Vladimir Korablin, and are licensed to the owners and users of the PureScript compiler project under the terms of the MIT license.

8484- [@zudov](https://github.com/zudov) (Konstantin Zudov) My existing contributions and all future contributions until further notice are Copyright Konstantin Zudov, and are licensed to the owners and users of the PureScript compiler project under the terms of the [MIT license](http://opensource.org/licenses/MIT).

8585- [@brandonhamilton](https://github.com/brandonhamilton) (Brandon Hamilton) My existing contributions and all future contributions until further notice are Copyright Brandon Hamilton, and are licensed to the owners and users of the PureScript compiler project under the terms of the [MIT license](http://opensource.org/licenses/MIT).

86+- [@bbqbaron](https://github.com/bbqbaron) (Eric Loren) My existing contributions and all future contributions until further notice are Copyright Eric Loren, and are licensed to the owners and users of the PureScript compiler project under the terms of the [MIT license](http://opensource.org/licenses/MIT).

8687

8788### Companies

8889

examples/failing/ConstraintFailure.pursnew file+13

@@ -0,0 +1,13 @@

1+-- @shouldFailWith NoInstanceFound

3+module Main where

5+import Prelude

7+data Foo = Bar

9+spin :: forall a. a -> Foo

10+spin x = Bar

11+

12+main = show <<< spin

13+

examples/failing/ConstraintInference.purs+1−1

@@ -1,4 +1,4 @@

1−-- @shouldFailWith NoInstanceFound

1+-- @shouldFailWith AmbiguousTypeVariables

33module Main where

src/Language/PureScript/AST/Declarations.hs+1

@@ -83,6 +83,7 @@ data SimpleErrorMessage

8383 | ConstrainedTypeUnified Type Type

8484 | OverlappingInstances (Qualified (ProperName 'ClassName)) [Type] [Qualified Ident]

8585 | NoInstanceFound Constraint

86+ | AmbiguousTypeVariables Type Constraint

8687 | UnknownClass (Qualified (ProperName 'ClassName))

8788 | PossiblyInfiniteInstance (Qualified (ProperName 'ClassName)) [Type]

8889 | CannotDerive (Qualified (ProperName 'ClassName)) [Type]

src/Language/PureScript/Errors.hs+7

@@ -118,6 +118,7 @@ errorCode em = case unwrapErrorMessage em of

118118 ConstrainedTypeUnified{} -> "ConstrainedTypeUnified"

119119 OverlappingInstances{} -> "OverlappingInstances"

120120 NoInstanceFound{} -> "NoInstanceFound"

121+ AmbiguousTypeVariables{} -> "AmbiguousTypeVariables"

121122 UnknownClass{} -> "UnknownClass"

122123 PossiblyInfiniteInstance{} -> "PossiblyInfiniteInstance"

123124 CannotDerive{} -> "CannotDerive"

@@ -261,6 +262,7 @@ onTypesInErrorMessageM f (ErrorMessage hints simple) = ErrorMessage <$> traverse

261262 gSimple (ExprDoesNotHaveType e t) = ExprDoesNotHaveType e <$> f t

262263 gSimple (InvalidInstanceHead t) = InvalidInstanceHead <$> f t

263264 gSimple (NoInstanceFound con) = NoInstanceFound <$> overConstraintArgs (traverse f) con

265+ gSimple (AmbiguousTypeVariables t con) = AmbiguousTypeVariables <$> (f t) <*> pure con

264266 gSimple (OverlappingInstances cl ts insts) = OverlappingInstances cl <$> traverse f ts <*> pure insts

265267 gSimple (PossiblyInfiniteInstance cl ts) = PossiblyInfiniteInstance cl <$> traverse f ts

266268 gSimple (CannotDerive cl ts) = CannotDerive cl <$> traverse f ts

@@ -636,6 +638,11 @@ prettyPrintSingleError (PPEOptions codeColor full level showWiki) e = flip evalS

636638 where

637639 go TUnknown{} = True

638640 go _ = False

641+ renderSimpleErrorMessage (AmbiguousTypeVariables t _) =

642+ paras [ line "The inferred type"

643+ , indent $ line $ markCode $ prettyPrintType t

644+ , line "has type variables which are not mentioned in the body of the type. Consider adding a type annotation."

645+ ]

639646 renderSimpleErrorMessage (PossiblyInfiniteInstance nm ts) =

640647 paras [ line "Type class instance for"

641648 , markCodeBox $ indent $ Box.hsep 1 Box.left

src/Language/PureScript/TypeChecker/Types.hs+1−1

@@ -111,7 +111,7 @@ typesOf bindingGroupType moduleName vals = withFreshSubstitution $ do

111111 let solved = foldMap (S.fromList . fdDetermined) typeClassDependencies

112112 let constraintTypeVars = nub . foldMap (unknownsInType . fst) . filter ((`notElem` solved) . snd) $ zip (constraintArgs con) [0..]

113113 when (any (`notElem` unsolvedTypeVars) constraintTypeVars) $ do

114− throwError . onErrorMessages (replaceTypes currentSubst) . errorMessage $ NoInstanceFound con

114+ throwError . onErrorMessages (replaceTypes currentSubst) . errorMessage $ AmbiguousTypeVariables generalized con

115115

116116 -- Check skolem variables did not escape their scope

117117 skolemEscapeCheck val'