[Hat] Hat bug report: Ambiguous occurrence `List'

[Bernard James POPE]

On Mon, Jun 21, 2004 at 05:48:09PM -0700, Fergus Henderson wrote:
> I am trying to get Hat working on a reasonably large and complicated project.
> Unfortunately it doesn't work.  I have cut down the code which triggers the
> problem to the following simple test case:
> 
>  | bash$ cat Foo/List.hs
>  | module Foo.List where
>  | 
>  | class List a b where
>  |         foo :: a -> b
>  | 
>  | main :: IO ()
>  | main = return ()
>  | 
>  | bash$ hmake -hat Foo/List
>  | hat-trans  Foo/List.hs
>  | Creating directories Hat Hat/Foo
>  | Wrote Hat/Foo/List.hs
>  | /usr/bin/haskell-compiler      -c -package hat -o Hat/Foo/List.o Hat/Foo/List.hs
>  | 
>  | Hat/Foo/List.hs:1:
>  |     Ambiguous occurrence `List'
>  |     It could refer to either `Hat.Hat.List', imported from Hat.Prelude at Hat/Foo/List.hs:30
>  |                           or `Hat.Foo.List.List', defined at Hat/Foo/List.hs:32
> 
> I am using hat-2.02.8 with ghc 6.2 on Debian Linux.

Hi Fergus,

As a temporary fix, that _might_ get you past this bug, you can modify the
file Hat/Foo/List.hs to say:

   import Hat.Prelude hiding (List) 

instead of

   import Hat.Prelude 

on about line 30.

There might be cases where this fails to fix the problem though.

Cheers,
Bernie.