On Tue, 20 Feb 2007 apfelmus@quantentunnel.de wrote:
Paul Moore wrote:
I'm after a function, sort of equivalent to map, but rather than mapping a function over a list of arguments, I want to map a list of functions over the same argument. The signature would be [a -> b] -> a -> [b], but hoogle didn't come up with anything.
It seems like an obvious analogue of map, so I'm pretty sure I'm missing something (otherwise, I'd just write it myself, and not bother :-))
Can anyone point me in the right direction?
It's also known as
sequence :: Monad m => [m b] -> m [b]
with m = (->) a
sequence :: [a -> b] -> (a -> [b])
This is the fabulous MonadReader.
Since there are a few questions, where 'sequence' is the answer - what about a 'sequence' honour Wiki page? I remember the combinatoric problem: http://www.haskell.org/pipermail/haskell-cafe/2006-June/015976.html