s> A system for representing natural numbers inductively using only two symbols, "0" (zero) and "s" (successor). This could be expressed as a recursive data type with the following Haskell definition: data Peano = Zero | succ Peano The number three, usually written "sss0", would be succ (succ (succ Zero)). Addition of Peano numbers can be expressed as a simple syntactic transformation: plus Zero n = n plus (succ m) n = succ (plus m n) (1995-03-28)
