gracjanpolak:
> Chaddaï Fouché <chaddai.fouche <at> gmail.com> writes:
> > 2008/7/22 Luke Palmer <lrpalmer <at> gmail.com>:
> > > A little formal reasoning reveals that sequence1 = sequence2 exactly
> > > when (>>=) is strict in its left argument. There are four common
> > > monads which are _not_: Identity, Reader, Writer, State (and RWS by
> > > extension).
> >
> > Still if that makes that much of a difference, maybe we could envision
> > putting a sequence' in the library ?
> >
>
> Yes, in my experiments this is to be or not to be. Stack space is limited.
> Also processing time goes down by 800%, so it is a big deal sometimes.
>
> Incomplete list of functions affected:
>
> sequence
> mapM
> foldM
> Text.ParserCombinators.Parsec.Combinator(many1,sepBy,endBy,manyTill)
> Text.ParserCombinators.ReadP(many,many1,count,sepBy,endBy,manyTill)
> ...
>
> As far as I know sequence could be specialized to IO monad and use my
> transformation.
>
> How do I reason if >>= for parsers is lazy in its first argument?
How about adding
Control.Monad.Strict
for the strict package?
http://hackage.haskell.org/cgi-bin/hackage-scripts/package/strict
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