!import "base" !Local
!import "list" !Local

incDecRev = y (self : matchList
  "1"
  (digit rest :
    matchBool
      (pair 48 (self rest))
      (pair (succ digit) rest)
      (equal? digit 57)))

showNumberRev_ = y (self n acc :
  matchBool
    acc
    (self (pred n) (incDecRev acc))
    (equal? n 0))

showNumber = (n :
  matchBool
    "0"
    (reverse (showNumberRev_ n t))
    (equal? n 0))