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Re: SRFI 105: Curly-infix-expressions

This page is part of the web mail archives of SRFI 105 from before July 7th, 2015. The new archives for SRFI 105 contain all messages, not just those from before July 7th, 2015.

David A. Wheeler scripsit:

> I have several concerns about cycle-detection in R7RS, which I think
> is otherwise shaping up pretty nicely.  Trying to deal with equal? led
> me to realize some weirdnesses with equal?, write, and display.  I'll
> see what I can do quickly.

Just to update you on what will appear in draft 7, based on the sixth

Write is being split into three procedures:

    write, which detects loops and prints datum labels (#n=, #n#) for

    write-simple, which does not detect loops (same as R5RS write).

    write-shared, which detects both loops and shared structure, printing
    datum labels for both.

Display will be the same as write.

> Fair enough.  But will *Scheme* ignore it properly when it IS the
> first character of a file? Guile, clisp, and many other Lisps will
> ignore #!...!# so that you can create Scripts in Scheme / Common Lisp
> / whatever.  That is really useful functionality, and one that I hate
> to interfere with.

I don't see that you're interfering with it.  What happens with shebang
lines is implementation-dependent.  If you are writing portable code,
you need to avoid them.  In any case, we already have #!fold-case and
#!no-fold-case in both R6RS and R7RS, as well as #!r6rs in R6RS (there
is no R7RS analogue).

> #!srfi-105
> #!c-expr
> ...something else...

C-expr could mean anything.  SRFI 105 is a unique name and tells you
where to look.

John Cowan  cowan@xxxxxxxx  http://www.ccil.org/~cowan
Thor Heyerdahl recounts his attempt to prove Rudyard Kipling's theory
that the mongoose first came to India on a raft from Polynesia.
        --blurb for Rikki-Kon-Tiki-Tavi