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? -- Gracjan _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
