peano arithmetic

from The Free On-line Dictionary of Computing (8 July 2008)

Peano arithmetic

   <mathematics> 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)