@hackage ghc-justdoit0.1.0.2

This plugin allows you to write

{-# OPTIONS_GHC -fplugin GHC.JustDoIt.Plugin #-}
module Test where

import GHC.JustDoIt

foo :: ((a -> r) -> r) -> (a -> ((b -> r) -> r)) -> ((b -> r) -> r)
foo = (…)

without having to write the actual implementation of foo.

See examples/Demo.hs for a few examples of what this plugin can do for you.