[r6rs-discuss] [Formal] need make-custom-textual-input-port and make-custom-textual-output-port

[Per Bothner]

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This message is a formal comment which was submitted to formal-comment at r6rs.org, following the requirements described at: http://www.r6rs.org/process.html
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Type: Defect
Priority: Major
Component: I/O
Version: 5.92

The procedures make-custom-binary-input-port and
make-custom-binary-output-port allow one to create
custom binary ports.  However, there seems to be
no way to create similar textual ports.  I guess
in theory one might be able to wrap a transcoder
around a custom binary port but that seems horribly
wrong when there is no underlying byte stream.

Specifically, it should be possible to implement
open-string-input-port and open-string-output-port
using purely public procedures.

Furthermore, open-string-input-port should return
a seekable port.  See my other comment.
'allow port position to be "magic cookie"'
-- 
	--Per Bothner
per at bothner.com   http://per.bothner.com/