[Scheme-reports] decoding strings from bytevectors

[Marijn <hkBst@x>]

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Hi,

I recently ran into this minor issue writing some R6RS code and would
like to know how R7RS addresses it.

Say you want to extract a string from a bytevector, but the bytevector
contains other information before and after the bytes that encode the
string data. In R6RS, AFAIK, you have to copy those bytes to a new
bytevector and then decode that entire bytevector to a string
(probably causing another copy operation). I think it would be useful
if something like


(define (string-decoder bytevector position length transcoder
  (bytevector->string
   (let ((bv (make-bytevector length)))
     (bytevector-copy!
      bytevector position bv 0 length)
     bv)
   transcoder) )


were supported directly by bytevector->string without the additional
bytevector-copy.

Marijn
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