[Haskell-cafe] Help understanding a partial application

Hi, I was browsing through the source code for Data.Foldable and having trouble comprehending it (which was kind of the point of browsing the code, so I could learn something ;) ) I'm looking at foldl foldl :: (c - d - c) - c - t d - c foldl f z t = appEndo (getDual (foldMap (Dual . Endo .

Re: [Haskell-cafe] Help understanding a partial application

Just expand out the function composition: Dual . Endo . flip f = (\x - Dual (Endo (flip f x))) which has the type d - Dual (Endo c). -- ryan On 8/26/07, Levi Stephen [EMAIL PROTECTED] wrote: Hi, I was browsing through the source code for Data.Foldable and having trouble

Re: [Haskell-cafe] Help understanding a partial application

Ryan Ingram wrote: Just expand out the function composition: Dual . Endo . flip f = (\x - Dual (Endo (flip f x))) which has the type d - Dual (Endo c). -- ryan Aha. I didn't get this straight away, but once I looked at the type signature for function composition, it became clear.