(define s:symbol (struct-type 's:symbol))
(define *symbols* (make-hash-table))

(define (make-symbol name)
  (let ([sym (make-struct s:symbol)])
    (struct-set! sym 0 (freeze! (copy-byte-string name)))
    (freeze! sym)))

(define (symbol? x)
  (and (struct? x) (eq? (struct-type x) s:symbol)))
 
(define (symbol->string sym)
  (struct-ref (type-check s:symbol sym) 0))

(define (string->symbol name)
  (or (hash-table-lookup *symbols* name)
      (let ([sym (make-symbol name)])
        (hash-table-insert *symbols* name sym)
        sym)))

(define *gensym-counter* 0)

(define (gensym [prefix "g"])
  (set! *gensym-counter* (fix+ *gensym-counter* 1))
  (make-symbol (byte-string-append prefix (number->string *gensym-counter*))))

(define (register-symbols syms)
  (when (pair? syms)
    (let ([sym (car syms)])
      (hash-table-insert *symbols* (symbol->string sym) sym))
    (register-symbols (cdr syms))))

; vim:set syntax=scheme sw=2 expandtab: