How does currying work?

Question

I\'m very new to Haskell and FP in general. I\'ve read many of the writings that describe what currying is, but I haven\'t found an explanation to how it actually works.

Answer 1

Something that may help is to think about how you could implement curry as a higher order function if Haskell didn't have built in support for it. Here is a Haskell implementation that works for a function on two arguments.

curry :: (a -> b -> c) -> a -> (b -> c)
curry f a = \b -> f a b

Now you can pass curry a function on two arguments and the first argument and it will return a function on one argument (this is an example of a closure.)

In ghci:

Prelude> let curry f a = \b -> f a b
Prelude> let g = curry (+) 5
Prelude> g 10
15
Prelude> g 15
20
Prelude> 

Fortunately we don't have to do this in Haskell (you do in Lisp if you want currying) because support is built into the language.