From: <tomas@tuxteam.de>
To: Christopher Dimech <dimech@gmx.com>
Cc: help-gnu-emacs@gnu.org, moasenwood@zoho.eu
Subject: Re: Executing part of the code instead of another
Date: Wed, 7 Oct 2020 16:01:50 +0200 [thread overview]
Message-ID: <20201007140150.GA2289@tuxteam.de> (raw)
In-Reply-To: <trinity-448160cc-9859-4856-a08d-13fc8b69d71c-1602078531474@3c-app-mailcom-bs01>
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On Wed, Oct 07, 2020 at 03:48:51PM +0200, Christopher Dimech wrote:
> It would be better if you explain to me this progn stuff
>
> Have tried an example like this
>
> (setq na 8)
> (setq nb 13)
> ( if (> nb na)
> progn (
> (message "nb > na condition [condition is true]")
> (message "nb > na condition [condition is true]")
> )
No. Written in Lisp, it's
(progn
(thing 1)
(thing 2)
...)
In C (and in conventional maths, you'd write it as you did
above).
Note that it's the same way as you write (message "foo")
[you don't write message("foo"), as you'd do in C or
Python or what not).
Progn is a form to bundle a sequence of forms, which are
evaluated one after the other. The value of progn is
that of the last form evaluated (that's the -n), as opposed
to prog1, which would do the same as progn, but return the
value of its first form.
Cheers
- t
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next prev parent reply other threads:[~2020-10-07 14:01 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-07 0:19 Executing part of the code instead of another Christopher Dimech
2020-10-07 0:50 ` Emanuel Berg via Users list for the GNU Emacs text editor
2020-10-07 0:55 ` Christopher Dimech
2020-10-07 1:05 ` Emanuel Berg via Users list for the GNU Emacs text editor
2020-10-07 7:01 ` Christopher Dimech
2020-10-07 7:13 ` Emanuel Berg via Users list for the GNU Emacs text editor
2020-10-07 7:20 ` Robert Pluim
2020-10-07 13:09 ` Christopher Dimech
2020-10-07 17:29 ` Nick Dokos
2020-10-07 18:01 ` Christopher Dimech
2020-10-07 9:38 ` Gregory Heytings via Users list for the GNU Emacs text editor
2020-10-07 9:46 ` Emanuel Berg via Users list for the GNU Emacs text editor
2020-10-07 9:53 ` Robert Pluim
2020-10-07 11:17 ` Emanuel Berg via Users list for the GNU Emacs text editor
2020-10-07 11:28 ` Robert Pluim
2020-10-07 13:28 ` Stefan Monnier
2020-10-07 13:40 ` Robert Pluim
2020-10-07 13:48 ` Christopher Dimech
2020-10-07 14:01 ` tomas [this message]
2020-10-07 14:05 ` Christopher Dimech
2020-10-08 17:43 ` Leo Butler
2020-10-07 15:15 ` Drew Adams
2020-10-18 23:02 ` Douglas Lewan
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