bug#30078: 27.0.50; Use lexical-binding for M-:

[Eli Zaretskii]

> From: Luis Gerhorst <privat@luisgerhorst.de>
> Date: Sat, 13 Jan 2018 18:50:36 +0100
> Cc: Eli Zaretskii <eliz@gnu.org>, monnier@IRO.UMontreal.CA,
>  30078@debbugs.gnu.org
> 
> 1) Make Elisp more approachable to newcomers. Lexical binding is the default 
> in most programming languages and thus more people are familiar with it. This 
> makes it easier for people to understand existing code since they don‘t have 
> to get used to implicit dynamic binding first, which the code may take 
> advantage of.

Do we know for a fact that most users who extend Emacs by writing
their own Lisp have background in Lisps and other similar languages
where lexical binding is the default?  If not, dynamic binding might
be easier to grasp for the newcomers.