Re: Predicate for true lists

[Eli Zaretskii]

> From: "Basil L. Contovounesios" <address@hidden>
> Date: Tue, 09 Apr 2019 21:12:49 +0100
> Cc: address@hidden
> 
> diff --git a/doc/lispref/internals.texi b/doc/lispref/internals.texi
> index 8ebe47d9ad..826818c380 100644
> --- a/doc/lispref/internals.texi
> +++ b/doc/lispref/internals.texi
> @@ -1031,10 +1031,13 @@ Writing Emacs Primitives
>  @file{lisp.h} contains the definitions for some important macros and
>  functions.
>  
> -  If you define a function which is side-effect free, update the code
> -in @file{byte-opt.el} that binds @code{side-effect-free-fns} and
> address@hidden so that the compiler optimizer
> -knows about it.
> +  If you define a function which is side-effect free, give it a
> address@hidden @code{side-effect-free} declaration (@pxref{Declare
> +Form}) or function property (@pxref{Symbol Plists}) so that the
> +compiler optimizer knows about it.  Alternatively, you can update the
> +code in @file{byte-opt.el} that binds @code{side-effect-free-fns} and
> address@hidden, but this approach is less
> +modular and no longer encouraged.

This should have a @cindex entry for "side-effect-free" and other
symbols referenced here.  Bonus points for adding some minimal
explanation what does "side-effect free function" mean.

Thanks.