From: Ian Price <ianprice90@googlemail.com>
To: Panicz Maciej Godek <godek.maciek@gmail.com>
Cc: "guile-user@gnu.org" <guile-user@gnu.org>
Subject: Re: and-let* is not composable?
Date: Wed, 11 Sep 2013 15:05:04 +0100 [thread overview]
Message-ID: <8761u7o3n3.fsf@Kagami.home> (raw)
In-Reply-To: <CAMFYt2bYp51FRHKHddTAEuLTZDCsK53TszMe-AzQxSzZXa04OA@mail.gmail.com> (Panicz Maciej Godek's message of "Wed, 11 Sep 2013 14:25:07 +0200")
Panicz Maciej Godek <godek.maciek@gmail.com> writes:
> That's not entirely true. I just need an extra pair of parentheses
> to do so. The semantics is certainly different than the one of
> Guile's curried definitions, but that's fine.
An identifier macro would be even better, but it's still not first
class.
> Well, while syntax-rules macros are quite easy to understand
> (at least from the user's point of view), although sometimes a little
> tricky, the syntax-case system I find still too difficult to use.
> define-macro, on the other hand, is very easy to explain
> even to beginner programmers, although the resulting macros
> are much more difficult to analyse.
If you, or the other people who are confused by syntax-case, can point
to the parts of the manual that confuse you, so we can clear them up, I
think we'd all appreciate it.
Fundamentally, syntax-case shouldn't be harder to use than define-macro
99% of the time, if you remember
- macros are functions from "syntax-objects" to syntax-objects
- syntax-objects are smart symbols
- syntax->datum to remove the smartness
- datum->syntax is for when you want to break hygiene (but syntax
parameters are better where applicable)
- use quasisyntax to construct lists of syntax-objects instead of
quasiquote to construct lists of symbols.
> The main problem with syntax-rules/syntax-case macros is
> the treatment of ellipses, which makes it difficult to create
> macros that create macros.
You can expand into ellipses with (... ...), it's ugly, but it's there.
> with a good name for that macro (and if so, the Guile's curried
> definitions are not curried either, at least in general: because
> you can (define ((f a b) c d) ...), getting a chain of 2-argument
> functions)
Indeed, I wasn't sure whether or not I should have mentioned it, but I
was told this is the "correct" name for that feature on comp.lang.scheme
a while back. I think it might have been Will Clinger, but I'd need to
double check.
--
Ian Price -- shift-reset.com
"Programming is like pinball. The reward for doing it well is
the opportunity to do it again" - from "The Wizardy Compiled"
next prev parent reply other threads:[~2013-09-11 14:05 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-09 17:35 and-let* is not composable? Panicz Maciej Godek
2013-09-09 20:26 ` Stefan Israelsson Tampe
2013-09-09 21:34 ` Ian Price
2013-09-10 13:42 ` Stefan Israelsson Tampe
2013-09-10 13:51 ` Ian Price
2013-11-02 2:39 ` Ian Price
2013-11-02 19:01 ` Ian Price
2013-09-10 17:57 ` Ian Price
2013-09-11 12:25 ` Panicz Maciej Godek
2013-09-11 14:05 ` Ian Price [this message]
2013-09-13 18:40 ` Panicz Maciej Godek
2013-09-14 8:19 ` Stefan Israelsson Tampe
2013-10-04 22:27 ` Panicz Maciej Godek
2013-10-05 8:00 ` Ian Price
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