main.saty

@require: stdjareport
@import: stage0

let-inline \show-int n = embed-string (arabic n)
in

document (|
  title = {サンプル文書};
  author = {組 版太郎};
|) '<
 +p {\show-int(~(gen (Let (Value (&1), fun x ->
                     (Let (Value (&2), fun y ->
                     x))))));}
>

stage0.saty

@stage: 0

type 'a ast =
    Value of 'a
  | Let of 'a ast * ('a ast -> 'a ast)


let gen-value c =
  &(let x = ~(c) in
    x
   )

let gen-let expr body =
  &(let e = ~(expr) in
    ~(body &e)
   )

let-rec gen ast = match ast with
  | Value (v)          -> gen-value v
  | Let (expr, body) -> gen-let (gen expr) (fun x -> gen (body (Value x)))