;;;; = and != on bools, a match over a bool, and keyword arms over a dyn.

(defstruct Flag [on bool])

(defn truth [n i32] bool (> n 0))

(defn is-same [a bool b bool] bool (= a b))

;; Exhaustive without a _ arm: true and false are every bool.
(defn word [b bool] str
  (match b
    true  "yes"
    false "no"))

(defn flipped [b bool] i32
  (match b
    false 0
    true  1))

(defn only-true [b bool] i32
  (match b
    true 1
    _    0))

;; Over a dyn :north is the arm (= d :north), beside numbers, strings and
;; bools, which are dyn values too.
(defn heading [d dyn] str
  (match d
    :north "up"
    :south "down"
    1      "one"
    "west" "left"
    true   "true"
    _      "other"))

(defn main [] i32
  (let [f (Flag {.on true})
        g (Flag {.on false})
        flags [true false true]]
    (print (is-same true true)) (print " ")
    (print (is-same true false)) (print " ")
    (print (!= true false)) (print " ")
    (print (= (.on f) (truth 3))) (print " ")
    (print (= (.on g) (truth 3))) (print " ")
    (print (!= (.on g) (at flags 1))) (print " ")
    (print (= true (at flags 0) (at flags 2))) (println "")
    (println (word true))
    (println (word (truth -1)))
    (print (flipped true)) (print (flipped false))
    (print (only-true true)) (print (only-true false)) (println "")
    (println (heading :north))
    (println (heading :south))
    (println (heading :east))
    (println (heading 1.0))
    (println (heading "west"))
    (println (heading true))
    (println (heading false))
    0))