-- Sebastian Fischer @sebfisch
-- https://twitter.com/sebfisch/status/752783154411429888
-- permission given https://twitter.com/sebfisch/status/754104295956615174
-- Fails on 41 example
-- No division by zero problems

import Data.List ( permutations )

solution = head
  [ (a,x,(b,y,(c,z,d)))
  | [a,b,c,d] <- permutations [2,5,6,6],
    ops <- permutations [((+),'+'),((-),'-'),((*),'*'),((/),'/')],
    let [u,v,w] = map fst $ take 3 ops,
    let [x,y,z] = map snd $ take 3 ops,
    (a `u` (b `v` (c `w` d))) == 17
  ]