ghc7 typing problem

[Simon Peyton-Jones]

Thanks.  We knew about this -- in flight changes happening now -- but I've added it as a new regression test even so.

Simon

| -----Original Message-----
| From: Christian Maeder [mailto:Christian.Maeder at dfki.de]
| Sent: 15 October 2010 17:53
| To: GHC Users Mailing List
| Cc: Simon Peyton-Jones
| Subject: ghc7 typing problem
| 
| Hi,
| 
| I've looked at:
| http://hackage.haskell.org/trac/ghc/blog/LetGeneralisationInGhc7
| 
| but still have a problem with the attached program that fails with:
| 
| GHCi, version 7.1.20101010: http://www.haskell.org/ghc/  :? for help Loading package
| ghc-prim ... linking ... done.
| Loading package integer-gmp ... linking ... done.
| Loading package base ... linking ... done.
| Loading package ffi-1.0 ... linking ... done.
| [1 of 1] Compiling Main             ( HasKey.hs, interpreted )
| 
| HasKey.hs:17:10:
|     Couldn't match type `key' with `key1'
|       because this skolem type variable would escape: `key1'
|     This skolem is bound by the instance declaration
|     In the instance declaration for `Ord (Keyed x)'
| 
| at the final instance for Ord.
| 
| The original code comes from
| http://hackage.haskell.org/packages/archive/uni-util/2.2.0.0/doc/html/Util-
| VariableSet.html
| 
| Cheers Christian