From: Michael Heerdegen <michael_heerdegen@web.de>
To: Marcin Borkowski <mbork@mbork.pl>
Cc: help-gnu-emacs@gnu.org
Subject: Re: How the backquote and the comma really work?
Date: Wed, 22 Jul 2015 00:08:25 +0200 [thread overview]
Message-ID: <877fptnoyu.fsf@web.de> (raw)
In-Reply-To: <87615mbo3z.fsf@mbork.pl> (Marcin Borkowski's message of "Tue, 14 Jul 2015 20:17:20 +0200")
Marcin Borkowski <mbork@mbork.pl> writes:
> Stupid me – again;-). No wonder ‘mci/read-list-contents’ appears twice,
> once, once in ‘mci/read’ and once in ‘mci/read-list-contents’ – it seems
> there’s no other way (though I can’t prove it formally).
I don't think every implementation needs to have it in two different
defuns.
> But now my problem is something different, and on a different level –
> a “metaproblem” in a sense. I’m still working on ‘mci/eval’; it now
> supports ‘progn’ forms and ‘setq’, and I have ‘cons’, ‘car’ and ‘cdr’ as
> symbols bound to their Elisp counterparts in the global environment of
> my MCI, and when I have lambdas (and write ‘mci/apply’, which should be
> relatively easy now), I’ll have more or less complete (though tiny)
> Lisp. I guess that adding backquote should be really straightforward
> then.
>
> So where’s the problem? Well, it’s quite a lot of fun to put it all
> together, and I’m learning a few things along the way, so it’s difficult
> to resist the temptation to add more stuff. Macros? ‘cond’ forms?
> ‘while’ forms? OTOH, my goal is *not* to recreate all Elisp (contrary
> to Scheme, Elisp is far from minimalistic, for instance, it has *a lot*
> of special forms which could, in principle, be macros - ‘if’, for
> example, or ‘let’, or ‘let*’). I definitely do not want to spend too
> much time on this – adding lots of special forms would soon cease to be
> fun, and once (and if!) I have macros, there’s really no use in adding
> them; also, I want to move on to other things.
Once you have macros, implementing the stuff you mentioned should not be
hard if you don't care about efficiency too much.
> So now my question is: does it make sense to play around with it more?
> Would a more complete Elisp interpreter written in Elisp be useful for
> anyone?
For learning purposes, it would be useful.
> If yes, I might consider publishing all my code sooner rather than
> later. And: if it’s interesting and/or useful for anybody, is there
> anything besides lambdas, a proper ‘mci/apply’ function and macros
> that definitely *should* be added? (One thing that comes to mind
> would be special (= dynamic) variables. I’m not sure whether I would
> like to add them – it might be too much work. OTOH, I’d learn to
> implement dynamic binding then...)
If you think you have learned what you wanted to, I would stop. Maybe
you feel like continuing working on it at a later point of time.
But hey, since you asked: Implementing nonlocal exits come to my mind as
a goal. And continuations would be cool. Implementing these are
probably harder lessons.
Regards,
Michael.
next prev parent reply other threads:[~2015-07-21 22:08 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-25 17:09 How the backquote and the comma really work? Marcin Borkowski
2015-06-25 17:33 ` Michael Heerdegen
2015-06-25 18:06 ` Marcin Borkowski
2015-06-25 18:22 ` Michael Heerdegen
2015-06-25 18:39 ` Marcin Borkowski
2015-06-25 18:44 ` Marcin Borkowski
2015-06-25 19:06 ` Michael Heerdegen
2015-07-10 11:36 ` Marcin Borkowski
2015-07-12 15:54 ` Michael Heerdegen
2015-07-12 19:55 ` Marcin Borkowski
2015-07-12 20:33 ` Marcin Borkowski
2015-07-14 18:17 ` Marcin Borkowski
2015-07-14 22:08 ` Emanuel Berg
2015-07-21 22:08 ` Michael Heerdegen [this message]
2015-07-24 13:01 ` Michael Heerdegen
2015-08-11 11:41 ` Marcin Borkowski
2015-08-12 15:29 ` Michael Heerdegen
[not found] ` <mailman.8207.1439393377.904.help-gnu-emacs@gnu.org>
2015-08-12 16:30 ` Pascal J. Bourguignon
2015-08-23 8:30 ` Marcin Borkowski
[not found] ` <mailman.110.1440318650.11330.help-gnu-emacs@gnu.org>
2015-08-23 16:46 ` Pascal J. Bourguignon
2015-07-21 21:54 ` Michael Heerdegen
2015-08-11 10:15 ` Marcin Borkowski
2015-08-11 17:20 ` Thorsten Jolitz
2015-08-12 15:01 ` Michael Heerdegen
2015-07-21 21:50 ` Michael Heerdegen
2015-06-25 18:10 ` Drew Adams
2015-06-25 18:40 ` Michael Heerdegen
2015-06-25 18:53 ` Marcin Borkowski
2015-06-25 19:39 ` Michael Heerdegen
2015-06-25 20:05 ` Drew Adams
2015-06-25 20:18 ` Marcin Borkowski
2015-06-25 20:37 ` Drew Adams
2015-06-25 23:55 ` Robert Thorpe
[not found] ` <mailman.5697.1435276533.904.help-gnu-emacs@gnu.org>
2015-06-26 1:41 ` Rusi
2015-06-26 14:24 ` Michael Heerdegen
[not found] ` <mailman.5716.1435328741.904.help-gnu-emacs@gnu.org>
2015-06-26 14:35 ` Rusi
2015-06-26 14:51 ` Michael Heerdegen
2015-06-25 18:46 ` Marcin Borkowski
2015-06-26 7:31 ` tomas
2015-06-26 13:48 ` Drew Adams
2015-06-26 14:06 ` tomas
2015-06-26 15:06 ` Emanuel Berg
2015-07-12 17:38 ` Vaidheeswaran C
[not found] <mailman.5657.1435252169.904.help-gnu-emacs@gnu.org>
2015-06-30 16:27 ` sokobania.01
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