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RE: [External] : Re: Always-true predicate?


From: Drew Adams
Subject: RE: [External] : Re: Always-true predicate?
Date: Wed, 17 Feb 2021 22:25:33 +0000

> Could you please make it optional? So that those who want the new
> behaviour of (apply nil) can get it by doing something like:
> 
>     M-x customize-variable RET apply-nil-will-not-segfault-anymore RET
> 
> There are many users and third-party packages which depend on the old
> behaviour. I'll show you stats in a minute...
> 
> Seriously: I remember one case when I tried to find CONSTANTLY or
> similar but failed. I wrote some LAMBDA form. No big deal.

Agreed, no big deal.
___

But if it's decided to do this, then clearly a function
that accepts an optional arg and just returns that arg
is preferable to either one that always returns `t' or
one that requires (instead of just accepts) an arg.

And the name `constantly' has a connotation of
repetition, which isn't relevant.  This is essentially
just the SKI logical combinator `K'.  Call it `constant'
or some such, perhaps.

OTOH, with Lisp, if the argument can return different
values when its evaluated then this really isn't a
constant-returning function.
___

But again, I agree with Teemu: YAGNI.



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