Re: Adding stuff to the core distro (was Re: Infix syntax)

[Daniel Skarda]

> BTW, does (ice-9 infix) handle tricky whitespace like in `#[2+4* 8]'?
> If not, you could use a simple macro rather than a read hash
> extension: `(infix 2 + 4 * 8)' rather than `#[2 + 4 * 8]'.  As a
> macro, `infix' would obey the usual module rules.

  Wow, that's clever. It seems I played with read hash extension too much that I
have not noticed simpler (and schemish) way... (On the other hand, #[] is 
shorter :-)

  Current infix module is divided to tokenizer (an arbitrary function without 
any
parameter, that returns new token) and parser (read-infix-expr tokenizer ....)
There is also function make-read-tokenizer, that can build tokenizer for
particular port. This tokenizer uses combination of read-char/read, it also
splits symbols, when there is #\[ #\] or #\, inside them. 

  No other tricky whitespace handling is performed (it would be dangerous, since
#\- and #\* are often used in scheme symbols).

  infix.scm proposal, second edition:
 ------------------------------------- 

(define-infix-macro NAME)

  define macro `NAME' which transforms infix syntax to scheme expressions. It
also defines variables *NAME-infix*, *NAME-prefix* hash tables (or rather
alists?) and *NAME-split-list*.

  NAME splits its arguments according characters in *NAME-split-list* list and
creates tokenizer, which successively feeds read-infix-expr with tokens.

(add-infix-operator NAME operator func paramers ...)
(add-prefix-operator NAME operator func paramers ...)

(add-infix-separator NAME character)

  I think that "clever" whitespace handling would be sometimes very confusing.
It is possible to split 4*8, but #\- will cause nightmare (foo-bar). IMHO it
would not be wise to split using symbol lookup (defined?) since it could cause
mysterious bugs ...

  I am going to rewrite infix.scm as soon as I get some spare time (first I
should stop spamming guile-devel with long emails, I guess :)

0.

ps: Sometimes I also use read-hash extension for shorter (sed|awk|perl|...)-like
regular expressions: #/foo.*bar/i, sometimes I also use srfi-10 #,(rx "foo.*bar"
icase). Do you think that other guilers would benefit from such hairy 
extensions?

I try to clean up my regexps.scm and post it later.