Rank-2 polymorphism & type inference

[Malcolm Wallace]

> Both GHC and Hugs reject this module if the type signature for
> test is omitted.  NHC (v1.00, 2000-09-15) falls over completely, with
>	Fail: Prelude.chr: bad argument

Rushing to the defence of nhc98 (as always!), I should point out
that nhc98 actually falls over here because of a bug in ghc.  (I
reported the bug several months ago.)  If your nhc98 compiler
was built by gcc, hbc, or nhc98 itself, then it gives a proper error
message here, viz:

    Couldn't simplify the context ((_180#) _171).
    Possible sources for the problem are:11:20

However, this is totally unrelated to the question of interest
regarding type inference.

Regards,
   Malcolm