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Re: Using #true and #false everywhere?


From: zimoun
Subject: Re: Using #true and #false everywhere?
Date: Tue, 20 Oct 2020 14:45:54 +0200

Hi Andreas,

On Tue, 20 Oct 2020 at 12:33, Andreas Enge <andreas@enge.fr> wrote:

> And since we are on the bikeshedding front, I feel like writing a second
> message.

You are playing the devil's lawyer role, right?


> On Fri, Oct 16, 2020 at 12:38:23PM +0200, Ludovic Courtès wrote:

> - The "non-typedness of booleans": Does "(if 1 2 3)" raise an exception or
>   work, and if the latter is true, what is the result? And if I replace
>   "1" by "0" or the empty list? (In Guix, this is related to the question:

This is a question about the standard, right?  It is not about #true
or #false vs #t or #f.

>   Do I need to add #t or #f at the end of a phase, or is the value of its
>   last statement sufficient?)

The question is how to know the value of the last statement.  And it
is Scheme/Guile question, right?  Not really about the #true vs #t,
isn't it?


> - What are the different procedures for comparing things?

The Guile manual explains well, isn't it?

<https://www.gnu.org/software/guile/manual/html_node/Equality.html>


Cheers,
simon

ps:
Well, one example showing all the points is, IMHO:

--8<---------------cut here---------------start------------->8---
scheme@(guix-user)> (define (f x) (when (> x 2) #true))
scheme@(guix-user)> (map f '(1 2 3 4))
$1 = (#<unspecified> #<unspecified> #t #t)
--8<---------------cut here---------------end--------------->8---

(whatever the comparison (> x 2) is; could be package related.)



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