operator-sections

This question already has answers here : What does $ mean/do in Haskell? (2 answers) Closed 5 years ago . This happens in the situation you want to apply bunch of functions to the same variable, it may look like this: map (\f->f 4) [odd, even] but from LYAH using $ make it very neat map ($ 4) [odd, even] why does it work. first I type it in ghci like $ 4 odd , it failed, then I type ($ 4) odd , which works fine. then I check the type of ($ 4) using :t which shows ($ 4) :: Num a => (a -> b) -> b , odd is odd :: Integral a => a -> Bool . It seems make sense, but still not clear to me. Can anyone

While I understand a little about currying in the mathematical sense, partially applying an infix function was a new concept which I discovered after diving into the book Learn You a Haskell for Great Good . Given this function: applyTwice :: (a -> a) -> a -> a applyTwice f x = f (f x) The author uses it in a interesting way: ghci> applyTwice (++ [0]) [1] [1,0,0] ghci> applyTwice ([0] ++) [1] [0,0,1] Here I can see clearly that the resulting function had different parameters passed, which would not happen by normal means considering it is a curried function (would it?). So, is there any