;FIXME sloppy, # only after srfi, which must be 1st
(define (module-name-element? x) (or (symbol? x) (fixnum? x)))

(define (module-name-element->string m) (->string m))

(define (reverse-module-name-elements->symbol l)
 (string->symbol (reverse-string-append (intersperse  l "."))) )

(define (srfi-module? mdl)
  (and (eq? 'srfi (car mdl))
       (pair? (cdr mdl))
       (number? (cadr mdl))) )

(define (canonicalize-srfi-name n)
  (string-append "srfi" "-" (number->string n)) )

(define (canonical-module-name x)
  (cond ((symbol? x)
          x )
        ((and (pair? x) (every module-name-element? x))
          (let loop ((mdl x) (l '()))
            (cond ((null? mdl)
                    (reverse-module-name-elements->symbol l))
                  ((and (null? l) ;1st time
                        (srfi-module? mdl))
                    (let ((md (canonicalize-srfi-name (cadr mdl))))
                      (loop (cddr mdl) (cons md l))) )
                  (else
                    (let ((md (module-name-element->string (car mdl))))
                      (loop (cdr mdl) (cons md l))) ) ) ) )
        (else
          #f ) ) )

(define (canonicalize-module-name x)
  (or (canonical-module-name x)
      (error 'canonicalize-module-name "invalid module name" x)) )