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

A simple example for using const is Data.Functor.(<$). With this function you can say: I have here a functor with something boring in it, but instead I want to have that other interesting thing in it, without changing the shape of the functor. E.g.

import Data.Functor

42 <$ Just "boring"
--> Just 42

42 <$ Nothing
--> Nothing

"cool" <$ ["nonsense","stupid","uninteresting"]
--> ["cool","cool","cool"]

The definition is:

(<$) :: a -> f b -> f a
(<$) =  fmap . const

or written not as pointless:

cool <$ uncool =  fmap (const cool) uncool

You see how const is used here to "forget" about the input.