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Re: current input & output ports

This page is part of the web mail archives of SRFI 68 from before July 7th, 2015. The new archives for SRFI 68 contain all messages, not just those from before July 7th, 2015.

Taylor Campbell <campbell@xxxxxxxxxxxxxxxxxx> writes:

> One thing that has always bothered me about Scheme's I/O system is the
> seemingly random presence of 'current ports.'  I haven't been able to
> find a rationale for the existence of the mechanism, and exactly what
> the 'current {input,output} port' is meant to be used for has never
> been clear to me.  Not only is the mechanism itself vague, but it also
> introduces unnecessary complexities in the interface: because the port
> argument to many operations is optional (which I believe Mike doesn't
> like anyway), the port must go last, which skews the possibility of
> other optional arguments and which is contrary to the very common
> convention of putting the important aggregate datum in the first
> argument.  Finally, the stream interface has no such similar 'current
> input stream' or 'current output stream,' so the stream operations are
> inconsistent with their port counterparts with optional arguments.

The more I think about it, the more I like it.  There are two

- The last vestige of R5RS compatibility goes out the window.  Does
  anyone care?

- This SRFI is then no longer suitable for ad-hoc debugging output
  (which, I think, provides the rationale for CURRENT-OUTPUT-PORT).
  This means somebody needs to write the Definitive printf SRFI.

Again, I'd like to get a sense of how much people care about R5RS
compatibility for the "default I/O system."

Cheers =8-} Mike
Friede, Völkerverständigung und überhaupt blabla