Fix: dont suggest "Use :" when OverloadedLists is enabled (fixes #1602)#1686
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Fix: dont suggest "Use :" when OverloadedLists is enabled (fixes #1602)#1686mgajda wants to merge 1 commit into
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…itchell#1602) With OverloadedLists, `\x -> [x]` and `(: [])` have different types: the former produces any IsList instance (Vector a, Set a, NonEmpty a, ...) while the latter specialises to [a]. Applying the suggestion produces code that no longer type-checks. Move the hint from data/hlint.yaml into a code-based hint in Hint/List.hs, gated on `not overloadedListsOn` (same pattern as ndmitchell#114 for "Use list literal" and ndmitchell#1674 for "Use unwords"). The hint still fires for `\x -> [x]` when the module does not enable OverloadedLists, and is suppressed per-file when it does. Tests added to the TEST block in Hint/List.hs. Self-test: 966 tests, all pass.
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Fixes #1602.
With
OverloadedLists,\x -> [x]and(: [])have different types: the former produces anyIsListinstance (Vector a,Set a,NonEmpty a, …) while the latter specialises to[a]. Applying the suggestion produces code that no longer type-checks.Move the hint from
data/hlint.yamlinto a code-based hint insrc/Hint/List.hs, gated onnot overloadedListsOn(same pattern as #114 for "Use list literal").The hint still fires for
\x -> [x]when the module does not enableOverloadedLists, and is suppressed per-file when it does.Tests added to the TEST block in
src/Hint/List.hs. Self-test: 966 tests, all pass.