traditional lisp macros

gistfile1.scm

;; outlet code for implementing traditional macro expansion

;; macros

(define (expand form)
  (cond
   ((variable? form) form)
   ((literal? form) form)
   ((macro? (car form))
    (expand ((macro-function (car form)) form)))
   ((eq? (car form) 'quote)
    form)
   ((eq? (car form) 'lambda)
    `(lambda ,(car (cdr form))
       ,@(map expand (cdr (cdr form)))))   
   (else (map expand form))))

(define _macros_ {})

(define (macro-function name)
  (ref _macros_ (symbol->string name)))

(define (install-macro name func)
  (put! _macros_ (symbol->string name) func))

(define (macro? name)
  (not (eq? (ref _macros_ (symbol->string name))
            undefined)))

;; compiler

(define (read src)
  (vector-to-list
   (reader grammar src '[begin])))

(install-macro 'define (lambda (form)
                         `(define* ,(car (cdr form))
                            ,@(cdr (cdr form)))))

(let ((src (fs.readFileSync "example.ol" "utf-8")))
  (pretty (expand (read src))))

;; (define (foo x y z)
;;   (+ x y z))
;;
;; expand to:
;;
;; (define* (foo x y z)
;;   (+ x y z))

No context provided; Coming from the blog post. Multiple undeclared variables. What are the prerequisites?