GHC 5.02 works fine for this program.  We're going to release it this
week.

Thanks for the test -- I've added it to our test suite!

Simon

| -----Original Message-----
| From: John Hughes [mailto:[EMAIL PROTECTED]] 
| Sent: 19 September 2001 18:00
| To: [EMAIL PROTECTED]
| Subject: Type-checker bug related to implicit parameters.
| 
| 
| 
| Hugs -98 (Feb 2001) rejects the following program (which 
| should be well-typed)
| 
| > foo :: ((?x :: Int) => b) -> Int -> b
| > foo s z = s with ?x = z
| 
| with the message
| 
| ERROR Bug.hs:2 - Inferred type is not general enough
| *** Expression    : foo
| *** Expected type : ((?x :: Int) => a) -> Int -> a
| *** Inferred type : ((?x :: Int) => a) -> Int -> Int
| 
| It seems to unify the type of the implicit parameter with the 
| type of the result.
| 
| GHC accepts this program (but generates wrong code).
| 
| John Hughes
| 
| _______________________________________________
| Hugs-Bugs mailing list
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