It's the Endo monoid. ?> :t ala Endo foldMap -- see newtype package ala Endo foldMap :: Foldable t => t (a -> a) -> a -> a ?> ala Endo foldMap [(+1), (*2)] 8 17 ?> :i ala ala :: (Newtype n o, Newtype n' o') => (o -> n) -> ((o -> n) -> b -> n') -> b -> o' -- Defined in Control.Newtype On 27/10/12 04:41, Greg Fitzgerald wrote:
Hi Haskellers,
I've recently found myself using the expression: "foldr (.) id" to compose a list (or Foldable) of functions. It's especially useful when I need to map a function over the list before composing. Does this function, or the more general "foldr fmap id", defined in a library anywhere? I googled and hoogled, but no luck so far.
Thanks, Greg
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