1-try.llrl

(no-implicit-std)

(import "builtin" some none ok err)
(import "std/boot/0-s" s:_)
(export try? try!)

(macro (try? s)
  (match s
    [(s:list _ (let x))
      (ok
        (s:list 'match x
          [s:list (s:list \some '(let x))
            'x]
          [s:list \none
            (s:list 'return \none)]))]
    [_
      (err "Expected (try? expr)")]))

(macro (try! s)
  (match s
    [(s:list _ (let x))
      (ok
        (s:list 'match x
          [s:list (s:list \ok '(let x))
            'x]
          [s:list (s:list \err '(let e))
            (s:list 'return (s:list \err 'e))]))]
    [_
      (err "Expected (try! expr)")]))