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|
; LIB
(let! just (\[a]
["maybe" "just" a]))
(let! nothing (\[]
["maybe" "nothing"]))
(let! unsafe-at (\[n seq]
(match seq
[]
(fatal! "unsafe-at out of bounds")
otherwise
(match n
0
(head seq)
otherwise
(unsafe-at (- n 1) (tail seq))))))
(let! unpack-just (unsafe-at 2))
(let! kind (unsafe-at 1))
(let! map (\[f m]
(match (kind m)
"just" (just (f (unpack-just m)))
"nothing" (nothing))))
(let! and-then (\[f m]
(match (kind m)
"just" (f (unpack-just m))
"nothing" (nothing))))
; TESTING
(let! print-line! (\[s]
(print! (concat s "\n"))))
(let! a (just 10))
(let! b (nothing))
(map (+ 5) a)
(map (+ 5) b)
(and-then (\[n] (just (+ n 5))) a)
(and-then (\[n] (just (+ n 5))) b)
(let! m (just 10))
(match m
(just _)
(print-line! (fmt "found just {0}!" [(unpack-just m)]))
(nothing)
(print-line! "found nothing!"))
;; (let! exports [
;; just
;; nothing
;; unpack-just
;; kind
;; map
;; and-then
;; ])
|
