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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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  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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