[Haskell-cafe] Re: General function to count list elements?

Achim Schneider barsoap at web.de
Mon Apr 20 09:57:01 EDT 2009

Lennart Augustsson <lennart at augustsson.net> wrote:

> On Sun, Apr 19, 2009 at 10:43 PM, Peter Verswyvelen
> <bugfact at gmail.com> wrote:
> > For example, suppose you have a predicate a -> Bool, and a list of
> > these predicates [a -> Bool], but you want to remove all functions
> > that are obviously equal in the C way from the list for
> > optimization... Okay big hack, and one could do this already with
> > reallyUnsafePtrEquality# I guess... 
> And when the need gets big enough you pull out StablePtr and use
> that. :)
Waaagh! Don't give him ideas, he's going to do it... Make yourself an
enum, generate your list, nub it, then transform it to a list of
functions. Always do everything with the least information sanely
feasible, and a function is more information than a value, even if you
can't get at it, anymore.

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