peano.matzo 602 B

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  1. isZero := { Z => True; <S,_> => False };
  2. add := { Z => { y => y }
  3. ; <S,x> => { y => add.x.<S,y> } };
  4. incr := add.<S,Z>;
  5. two := <S,<S,Z>>;
  6. four := <S,<S,<S,<S,Z>>>>;
  7. if := { True => { x => { _ => x } }
  8. ; False => { _ => { y => y } }
  9. };
  10. minusOne := { Z => Z; <S,x> => x };
  11. puts "S is " S;
  12. puts "Z is " Z;
  13. puts "True is " True;
  14. puts "False is " False;
  15. puts "Is 0 zero?";
  16. puts isZero.Z;
  17. puts "Is 4 zero?";
  18. puts isZero.four;
  19. puts "2 + 4 = ";
  20. puts add.four.two;
  21. puts "Is zero zero?";
  22. puts if.(isZero.Z)."yes"."no";
  23. puts "Is 0+1 zero?";
  24. puts if.(isZero.(incr.Z))."yes"."no";