(define-module (guile-syntax colon-keyword) #:export (colon-keyword))

(define (colon-keyword exp)
  (let lp ((lst exp))
    (cond 
     ((null? lst) exp)
     ((pair? lst)
      (set-car! lst (colon-keyword (car lst)))
      (if (pair? (cdr lst))
          (lp (cdr lst))
          (begin (set-cdr! lst (colon-keyword (cdr lst)))
                 (lp '()))))
     ((symbol? lst)
      (let ((str (symbol->string lst)))
        (if (char=? (string-ref str 0) #\:)
            (symbol->keyword (string->symbol (substring str 1)))
            lst)))
     ((vector? lst)
      (let lp2 ((i 0))
        (if (>= i (vector-length lst))
            lst
            (begin (vector-set! lst i (colon-keyword (vector-ref lst i)))
                   (lp2 (+ i 1))))))
     (else lst))))