SATySFiでoptionalな型をつける方法

?:でoptional引数として定義する

@require: stdja

let-inline ctx \sugoi ?:prefix s =
  let p = match prefix with
    | None -> `すごい`
    | Some(p) -> p
  in
  read-inline ctx (embed-string (p ^ s))
in

document (|
  author = { Seiei MIYAGI };
  show-title = true;
  show-toc = false;
  title = { SATySFiでoptional }
|) '<
 +p { \sugoi(`ねむい`); }
 +p { \sugoi?:(`やばい`)(`ねむい`); }
>

実行結果

matchでNoneやSomeにマッチさせる

sugoi.saty

@require: stdja

let-inline ctx \sugoi s =
  let s = match s with
    | None -> `すごい`
    | Some(s) -> s
  in
  read-inline ctx (embed-string s)
in

document (|
  author = { Seiei MIYAGI };
  show-title = true;
  show-toc = false;
  title = { SATySFiでoptional }
|) '<
 +p { \sugoi(None); }
 +p { \sugoi(Some(`すごくない`)); }
>

実行結果