[Haskell-cafe] Fwd: Backward compatibility

[Raphael Gaschignard]

On Sun, May 5, 2013 at 8:25 PM, Simon Marechal <simon at banquise.net> wrote:

> I ran into this kind of trouble when I was starting to learn Haskell. I
> had error messages like that :
>
> test.hs:1:8:
>     Could not find module `List'
>     It is a member of the hidden package `haskell98-2.0.0.2'.
>     Use -v to see a list of the files searched for.
>
> I then proceeded to figure how to include this haskell98 package, and
> later ran into other problems. Perhaps this message could be hard coded
> to tell the user that this is deprecated code, and he should use
> Data.List instead.
>

Forgive me if I'm wrong, but I feel like I've seen such "suggestions" in
GHC errors before.

If so, does that mean there's some sort of mechanism in the compiler
already in place for such error recognition? Like some simple pattern
stuff?  If not, I think that it might not be bad to consider this stuff
(misused packaged, changed semantics that create compiler errors), and to
put something into place for future modifications. This could make it a lot
easier to deal with unmaintained code.
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