GHC and Haskell 98

Paterson, Ross R.Paterson at
Sat Jun 18 14:57:06 CEST 2011

Simon PJ writes:
> But if you say
>         ghc -c Main.hs -package base -package haskell98
> then the (implicit) import of 'Prelude' will say "Ambiguous module name: Prelude", because it's exported by both 'base' and 'haskell98'.
> [...]
> So:    Under Plan A, some Hackage packages will become un-compilable,
>        and will require source code changes to fix them.  I do not have
>        any idea how many Hackage packages would fail in this way.

At a crude count, there are 368 packages on hackage that depend on both
base and haskell98, and thus will be compiled with a fatal command line
like the above.  Of these, somewhere between 105 and 199 currently
don't build (uncertain because I've only tried to build libraries).
So this change will probably break around 200 packages.

On a different point, whatever you do with Prelude you'll probably also
want to do with Foreign and Numeric.

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