Kind error in GHC-7.4.1, works in GHC-7.2.2

Roel van Dijk vandijk.roel at
Sun Feb 12 16:58:58 CET 2012

Thank you for the explanation. I now understand the problem. I have
rewritten the code using some parenthesis.


2012/2/10 Simon Peyton-Jones <simonpj at>:
> It should not have worked before.  Consider
>        I#  $   3#
> ($) is a polymorphic function and takes two *pointer* arguments.  If we actually called it with I# and 3# as arguments we might seg-fault when we call the GC when allocating the box.
> Polymorphic type variables (in this case in the type of ($)) can only be instantiated with boxed types.
> Simon

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