module SkewNat where

type SkewNat = [Int] -- increasing list of powers of 2^{k+1}-1

inc :: SkewNat -> SkewNat
inc ws@(w1 : w2 : rest)
   | w1 == w2  = 1 + w1 + w2 : rest
   | otherwise = 1           : ws
inc ws         = 1           : ws

dec :: SkewNat -> SkewNat
dec (1 : ws) = ws
dec (w : ws) = (w `div` 2) : (w `div` 2) : ws