On Jun 10, 2010, at 17:38 , Martin Drautzburg wrote:
instance Applicative Named where pure x = Named "" x (Named s f) <*> (Named t v) = Named (s ++ "(" ++ t ++ ")") (f v)Applicative. Need to study that
The above is just the Functor, rephrased in Applicative style. <*> is exactly fmap. Likewise, Monad has a function "liftM" which is exactly fmap. (For historical reasons, these are not related the way they should be: all Monads should be Applicatives, all Applicatives should be Functors, and all Functors should be instances of an even more primitive class Pointed.)
According to Hoogle permutations should be in Data.List. Mine (GHCI 6.8.2) does not seem to have it. Seems to have something to do with "base", whateverthat is.
Things have gradually been moving out of base; you probably need to install "containers" from Hackage.
-- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allb...@kf8nh.com system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu electrical and computer engineering, carnegie mellon university KF8NH
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