[Haskell-cafe] foldr (.) id

[Nick Vanderweit]

Funny, I was thinking this morning about using something like this to convert 
to/from Church numerals:

church n = foldl (.) id . replicate n
unchurch f = f succ 0


I think it's a nice pattern.

Nick

On Friday, October 26, 2012 11:41:18 AM 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