Improve warnings for use of "forall" without -XExistentialQuantification
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.
Trac metadata
Trac field | Value |
---|---|
Version | 6.8.3 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | Unknown |
Architecture | Unknown |