Functions: Dak Tour

; Functions are varied and colorful.

; Simple function:
(fn add [a b]
  (+ a b))
(prn (add 40 1))

; Async function:
(fn@ add-promises [a b]
  (+ @a @b))
(prn @(add-promises (Promise.resolve 40) (Promise.resolve 2)))

; Generator function:
(fn* powers [n count]
  (let [current 1]
    (for [i 0 count]
      (yield (*= current n)))))
(for-of [v (powers 2 5)]
  (prn v))

; Async generator function:
(fn@* foo [a b]
  (yield (inc @a))
  (yield (inc @b)))
(for@ [v (foo (Promise.resolve 41) (Promise.resolve -43))]
  (prn v))

; Exported function:
(fn ^:export plus [a b]
  (+ a b))

; Exported default function:
(fn ^:export ^:default [a b]
  (- a b))

; Declaration syntax:
(fn ^:decl TheClass [a]
  (set this.answer a))
(prn (TheClass. 42))

; Explicit return is available:
(fn until [a]
  (while true
    (if (= (++ a) 42)
      (return :boom))))
(prn :returned (until 40))

; Yield & Yield* are available:
(fn* it [a]
  (yield (++ a))
  (yield* [(++ a) (++ a)]))
(for-of [v (it 39)]
  (prn "it:" v))