Church-encoding of `Option`/Maybe` in Purescript

option.purs

module Main where

import Prelude
import Control.Monad.Eff.Console
import Data.Foldable (foldMap)
import TryPureScript



type Option a = forall b. (a -> b) -> b -> b

some :: forall a. a -> Option a
some a = \f -> \_ -> f a

none :: forall a. Option a
none = \_ -> \g -> g



main = render $ foldMap (h1 <<< text) results
  where
    results = [
      some "hello world"  id "nothing to see here",
      none                id "nothing to see here"
    ]



-- see http://try.purescript.org/?gist=8eb5f6823fb4d3a447109718f1b4e5c3&session=4cb2af31-96b0-7c3c-ed4c-a37170a211ba