Request: bytevector->string and string->bytevector

I was able to make my own, so this is low priority for me, but I should use the ones from (rnrs). Here are mine:

Ikarus Scheme version 0.0.3+ (revision 1527, build 2008-07-02)
Copyright (c) 2006-2008 Abdulaziz Ghuloum

>
  (define (bytevector->string bv t)
    (call-with-port (open-bytevector-input-port bv t)
      (lambda (tcip)
        (let ([r (get-string-all tcip)])
          (if (eof-object? r) "" r)))))
>
  (define (string->bytevector str t)
    (call-with-bytevector-output-port
      (lambda (tcop)
        (put-string tcop str))
      t))
>
> (string->bytevector "This is a sentence." (native-transcoder))
#vu8(84 104 105 115 32 105 115 32 97 32 115 101 110 116 101 110 99 101 46)
> (bytevector->string #vu8(40 40 206 187 32 40 120 41 32 40 120 32 120 41 41 32 40 206 187 32 40 120 41 32 40 120 32 120 41 41 41) (native-transcoder))
"((λ (x) (x x)) (λ (x) (x x)))"
>