What's the point of 'const' in the Haskell Prelude?

Question

Looking through the Haskell Prelude, I see a function const:

const x _ = x

I can\'t seem to find anything relevant regarding t

Answer 1

To add to hammar's excellent direct answer: humble functions like const and id are really useful as a higher order function for the same reason that they are fundamental in the SKI combinator calculus.

Not that I think haskell's prelude functions were modeled consciously after that formal system or anything. It's just that creating rich abstractions in haskell is very easy, so you often see these types of theoretical things emerge as practically useful.

Shameless plug, but I blogged about how the Applicative instance for (->) are actually the S and K combinators here, if that's the kind of thing you're into.