b17a4f0 · elk · git.iko.soy

git.iko.soy/elk

Better error messages for bad record accesses

Add Hint specifically about record access. Instead of showing a type diff, only show the type of the record being accessed. Seemed more confusing than helpful to keep showing the { a | field : b } type.

commitb17a4f051af5780950b790eb50ecb4093c699ab0 authorEvan Czaplicki <evancz@users.noreply.github.com> dateTue 20 Sep 2016, 16:58 (10 years ago) parenta2a2fc0

3 files changed+59−8

compare with master

unifiedsplit

src/AST/Expression/General.hs+20 src/Reporting/Error/Type.hs+31−5 src/Type/Constrain/Expression.hs+8−3

src/AST/Expression/General.hs+20

@@ -8,6 +8,8 @@ enrich the AST with more information.

88-}

99module AST.Expression.General where

1010

11+import qualified Data.List as List

12+

1113import qualified AST.Effects as Effects

1214import qualified AST.Literal as Literal

1315import qualified AST.Module.Name as ModuleName

@@ -88,6 +90,24 @@ tuple expressions =

8890 Data ("_Tuple" ++ show (length expressions)) expressions

8991

9092

93+collectFields :: (Var.ToString var) => Expr ann def var typ -> Maybe String

94+collectFields expr =

95+ collectFieldsHelp expr []

96+

97+

98+collectFieldsHelp :: (Var.ToString var) => Expr ann def var typ -> [String] -> Maybe String

99+collectFieldsHelp (A.A _ expr) fields =

100+ case expr of

101+ Var var ->

102+ Just (List.intercalate "." (Var.toString var : fields))

103+

104+ Access record field ->

105+ collectFieldsHelp record (field : fields)

106+

107+ _ ->

108+ Nothing

109+

110+

91111collectApps :: Expr ann def var typ -> [Expr ann def var typ]

92112collectApps annExpr@(A.A _ expr) =

93113 case expr of

src/Reporting/Error/Type.hs+31−5

@@ -75,6 +75,7 @@ data Hint

7575 | Pattern Pattern

7676 | Shader

7777 | Lambda

78+ | Access (Maybe String) String

7879 | Record

7980 -- effect manager problems

8081 | Manager String

@@ -145,11 +146,12 @@ mismatchToReport localizer (MismatchInfo hint leftType rightType maybeReason) =

145146 report =

146147 Report.report "TYPE MISMATCH"

147148

149+ typicalHints =

150+ Maybe.maybeToList (reasonToString =<< maybeReason)

151+

148152 cmpHint leftWords rightWords extraHints =

149153 comparisonHint localizer leftType rightType leftWords rightWords

150− ( Maybe.maybeToList (reasonToString =<< maybeReason)

151− ++ map toHint extraHints

152− )

154+ (typicalHints ++ map toHint extraHints)

153155 in

154156 case hint of

155157 CaseBranch branchNumber region ->

@@ -446,6 +448,30 @@ mismatchToReport localizer (MismatchInfo hint leftType rightType maybeReason) =

446448 []

447449 )

448450

451+ Access (Just body) field ->

452+ let

453+ header =

454+ "`" ++ body ++ "` does not have a field named `" ++ field ++ "`."

455+ in

456+ report Nothing header $ Help.stack $

457+ [ Help.reflowParagraph $ "The type of `" ++ body ++ "` is:"

458+ , indent 4 $ dullyellow $ RenderType.toDoc localizer leftType

459+ , Help.reflowParagraph $ "Which does not contain a field named `" ++ field ++ "`."

460+ ]

461+ ++ typicalHints

462+

463+ Access Nothing field ->

464+ let

465+ header =

466+ "Cannot access a field named `" ++ field ++ "`."

467+ in

468+ report Nothing header $ Help.stack $

469+ [ Help.reflowParagraph $ "You are trying to get `" ++ field ++ "` from a value with this type:"

470+ , indent 4 $ dullyellow $ RenderType.toDoc localizer leftType

471+ , Help.reflowParagraph $ "It is not in there!"

472+ ]

473+ ++ typicalHints

474+

449475 Record ->

450476 report

451477 Nothing

@@ -653,7 +679,7 @@ reasonToString reason =

653679 (fields, maybeDeepReason) =

654680 collectFields reason

655681

656− mabyeDocs =

682+ maybeDocs =

657683 reasonToStringHelp =<< maybeDeepReason

658684

659685 starter =

@@ -667,7 +693,7 @@ reasonToString reason =

667693 _ ->

668694 Just $ "Problem at `" ++ List.intercalate "." fields ++ "`. "

669695 in

670− case (starter, mabyeDocs) of

696+ case (starter, maybeDocs) of

671697 (Nothing, Nothing) ->

672698 Nothing

673699

src/Type/Constrain/Expression.hs+8−3

@@ -110,9 +110,14 @@ constrain env annotatedExpr@(A.A region expression) tipe =

110110 do c' <- constrain env e x

111111 return (x ==> t, c /\ c')

112112

113− E.Access expr label ->

114− exists $ \t ->

115− constrain env expr (record (Map.singleton label tipe) t)

113+ E.Access expr field ->

114+ exists $ \recordType ->

115+ exists $ \ext ->

116+ do recordCon <- constrain env expr recordType

117+ let maybeBody = E.collectFields expr

118+ let desiredType = record (Map.singleton field tipe) ext

119+ let fieldCon = CEqual (Error.Access maybeBody field) region recordType desiredType

120+ return $ recordCon /\ fieldCon

116121

117122 E.Update expr fields ->

118123 exists $ \t ->