Improve warnings for use of "forall" without -XExistentialQuantification
|Reported by:||dmhouse||Owned by:|
|Type of failure:||Difficulty:||Unknown|
|Test Case:||Blocked By:|
Here's a GHCi session:
Prelude> let foo :: forall a. a; foo = undefined <interactive>:1:19: Illegal operator `.' in type `forall a . a' (Use -XTypeOperators to allow operators in types) Prelude> let foo :: forall a. Show a => a; foo = undefined <interactive>:1:28: parse error on input `=>'
Both of these errors could be improved, I think, by detecting the use of 'forall' as a type variable name, and suggesting -XExistentialQuantification if it's being used.
Change History (3)
comment:1 Changed 6 years ago by simonpj
- Difficulty set to Unknown
- Resolution set to fixed
- Status changed from new to closed