如何在guile scheme中擴展宏？

Question

我正在嘗試在詭計中寫let over lambda defmacro/g!。我有這個：

(use-modules (srfi srfi-1)) 

(define (flatten x) 
    (let rec ((x x) (acc '())) 
     (cond ((null? x) acc) 
       ((not (pair? x)) (cons x acc)) 
       (else 
       (rec (car x) 
        (rec (cdr x) acc)))))) 

(define (g!-symbol? s) 
    (and (symbol? s) 
     (let ((symbol-string (symbol->string s))) 
     (and (> (string-length symbol-string) 2) 
       (equal? (string-downcase (substring symbol-string 0 2)) "g!"))))) 


(define-macro (define-macro/g! name-args . body) 
    (let ((syms (delete-duplicates 
       (filter g!-symbol? (flatten body))))) 
    `(define-macro ,name-args 
     (let ,(map 
       (lambda (s) 
        `(,s (gensym ,(substring (symbol->string s) 2)))) 
       syms) 
      ,@body)))) 

但是當我嘗試宏展開define-macro/g！使用此：

(use-modules (language tree-il)) 
(tree-il->scheme (macroexpand '(define-macro/g! (foo . body) `(let ((g!car ,(car body))) g!car)))) 

我有這樣的：

$15 = (if #f #f) 

爲什麼我有這樣的結果？如何擴展define-macro/g!？

Answer 1

我需要使用此代碼：

(define macro '(define-macro/g! (foo . body) `(let ((g!car ,(car body))) g!car))) 
(tree-il->scheme (macroexpand macro 'c '(compile load eval)))