nanopass-compiler framework examples

remove-one-armed-if.scm

(import (nanopass) (rnrs))

(define (primitive-procedure? x)
  (or (eq? x 'eq?)
      (eq? x 'symbol?)
      (eq? x 'boolean?)))

(define-language piyo-lang
  (terminals
    (primitive-procedure (proc))
    (boolean (b))
    (symbol (x)))
  (Expression (e)
    proc
    b
    x
    (if e e1)
    (if e e1 e2)
    (e e* ...)))

(define-language piyo-removed-one-armedif-lang
   (extends piyo-lang)
   (Expression (e)
     (- (if e e1))))

(define-pass remove-one-armed-if :
   piyo-lang (e) -> piyo-removed-one-armedif-lang ()
   (Expression : Expression (ir) -> Expression ()
      ((if ,e ,e1) `(if ,e ,e1 #f ))))


(define-parser parse-piyo-lang piyo-lang)
(define-parser parse-piyo-removed-one-armedif-lang
               piyo-removed-one-armedif-lang)

(display (unparse-piyo-removed-one-armedif-lang (remove-one-armed-if (parse-piyo-lang '(if a b)))))
(newline)