Post #2543705

Problem of the day: Derive a fused function equal to `dupLast . dupLast` where dupLast [] = [] dupLast [x] = [x,x] dupLast (x:xs) = x : dupLast xs Experienced functional programmers might see at a glance what the fused function looks like, but how do we derive it formally from the definition of `dupLast`? #haskell #functionalprogramming