!import "base.tri" !Local
!import "list.tri" !Local
!import "lazy.tri" !Local

match_ = y (self value patterns :
  triage
    t
    (_ : t)
    (pattern rest :
      triage
        t
        (_ : t)
        (test result :
          if (test value)
             (result value)
             (self value rest))
        pattern)
    patterns)

match = (value patterns :
  match_ value (map (sublist :
    pair (head sublist) (head (tail sublist)))
    patterns))

otherwise = const (t t)

cond_ self patterns =
  lazyList
    (_ : t)
    (pattern rest :
      matchPair
        (testK actionK :
          lazyBool
            actionK
            (_ : self rest)
            (testK t))
        pattern)
    patterns

cond patterns = y cond_ patterns

guard testK actionK = pair testK actionK