> > 2) Is there a reason to not use mapM3 above? > > Yes, there certainly is. mapM3 is not equivalent to mapM; it is too strict: > > *Main> take 3 $ head $ mapM return [1,2,3,4,undefined] > [1,2,3] > *Main> take 3 $ head $ mapM3 return [1,2,3,4,undefined] > [*** Exception: Prelude.undefined > > So, like foldl', mapM3 seems a viable alternative for mapM, but not a > replacement.
Wow. A 10x slowdown for a very commonly used function that in 99.8% of all use cases has no need for the extra laziness at all. No wonder some people say Haskell is a toy language... /Niklas _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
