doc-src/Codegen/Thy/examples/nat_binary.ML
author wenzelm
Wed, 18 Aug 2010 23:44:50 +0200
changeset 38479 e628da370072
parent 30226 2f4684e2ea95
permissions -rw-r--r--
more efficient Markup_Tree, based on branches sorted by quasi-order; renamed markup_node.scala to markup_tree.scala and classes/objects accordingly; Position.Range: produce actual Text.Range; Symbol.Index.decode: convert 1-based Isabelle offsets here; added static Command.range; simplified Command.markup; Document_Model.token_marker: flatten markup at most once; tuned;

structure Nat = 
struct

datatype nat = Dig1 of nat | Dig0 of nat | One_nat | Zero_nat;

fun plus_nat (Dig1 m) (Dig1 n) = Dig0 (plus_nat (plus_nat m n) One_nat)
  | plus_nat (Dig1 m) (Dig0 n) = Dig1 (plus_nat m n)
  | plus_nat (Dig0 m) (Dig1 n) = Dig1 (plus_nat m n)
  | plus_nat (Dig0 m) (Dig0 n) = Dig0 (plus_nat m n)
  | plus_nat (Dig1 m) One_nat = Dig0 (plus_nat m One_nat)
  | plus_nat One_nat (Dig1 n) = Dig0 (plus_nat n One_nat)
  | plus_nat (Dig0 m) One_nat = Dig1 m
  | plus_nat One_nat (Dig0 n) = Dig1 n
  | plus_nat m Zero_nat = m
  | plus_nat Zero_nat n = n;

end; (*struct Nat*)