; Iter 15f — fourth consumer demo. Drives every std_pair combinator
; once. fst/snd are stable at 7/9; swap reverses; map_first/map_second
; demonstrate the Pair<a, b> -> Pair<c, b> / Pair<a, c> reshape with
; b/a held rigid.

(module std_pair_demo

  (import std_pair)

  (fn inc
    (doc "Add 1. Used as the (a -> c) arg.")
    (type (fn-type (params (con Int)) (ret (con Int))))
    (params x)
    (body (app + x 1)))

  (fn double
    (doc "Multiply by 2. Used as the (b -> c) arg.")
    (type (fn-type (params (con Int)) (ret (con Int))))
    (params x)
    (body (app * x 2)))

  (fn main
    (doc "Drive every combinator. Expected (per line): 7, 9, 9, 7, 8, 18.")
    (type (fn-type (params) (ret (con Unit)) (effects IO)))
    (params)
    (body
      (seq (do io/print_int (app std_pair.fst (term-ctor std_pair.Pair MkPair 7 9)))
      (seq (do io/print_int (app std_pair.snd (term-ctor std_pair.Pair MkPair 7 9)))
      (seq (do io/print_int (app std_pair.fst (app std_pair.swap (term-ctor std_pair.Pair MkPair 7 9))))
      (seq (do io/print_int (app std_pair.snd (app std_pair.swap (term-ctor std_pair.Pair MkPair 7 9))))
      (seq (do io/print_int (app std_pair.fst (app std_pair.map_first  inc    (term-ctor std_pair.Pair MkPair 7 9))))
           (do io/print_int (app std_pair.snd (app std_pair.map_second double (term-ctor std_pair.Pair MkPair 7 9))))))))))))