GHC and Haskell 98

Simon Marlow marlowsd at
Fri Jun 24 13:30:56 CEST 2011

On 18/06/2011 11:20, Malcolm Wallace wrote:
> As one of the few people who has habitually used Haskell'98 wherever
> possible, I favour plan A.  As I recently discovered, in ghc 7 it is
> already very fragile to attempt to depend on both the base and
> haskell98 packages simultaneously.  In most cases it simply doesn't
> work.  Removing those few remaining cases where it happens to work by
> accident would be a good move.

This is a good point - as the APIs in base diverge more and more from 
those in haskell98, the illusion that you can use both at the same time 
becomes harder to maintain.  For example, the Random class from 
System.Random is now different from the one in haskell98's Random, so 
mixing the two doesn't work.

While the breakage of existing code is definitely regrettable, I'm 
slightly in favour of plan A.  In most cases the fixes will be a simple 
renaming of imports (we could probably make a script to do this, even).

Also plan A matches what we do for haskell2010, where we really have no 
choice because all the modules overlap with base.


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