Functional Programming: A PragPub Anthology

A Quick Exercise

Let’s see how much Haskell you can understand just by first grasping an informal, hand-wavy solution and then looking at the corresponding code. It’s very much a “think in data” solution, but also probably quite different from how you’ve seen this kind of problem approached before. Without modulo division or if statements, I give you “Functional Fizz Buzz.”

The task is this: you want Fizz every three steps, and Buzz every five steps. We note that sometimes the cycles coincide. Let’s talk cycles then.

threes = cycle ["", "", "Fizz"]
fives  = cycle ["", "", "", "", "Buzz"]

cycle is defined like this (the real library def is more efficient, but less clear):

cycle xs = xs ++ cycle xs   -- SIMPLE version of lib

So threes just ...