RE: Imports / inclusion of s.el into Emacs

[Drew Adams <drew.adams@oracle.com>]

>> But concat is not only about strings.  Will
>> we have 3 different aliases?  And what about the
>> case where each argument is of a different type?

Exactly.

> I think "seq-concat-to-string" is a better choice here.
> We can remove the "to-string".
>
> That or "seq-join" with a default separator to "" ?

A character is not a sequence.  `concat' is not
about concatenating sequences to return a string.

`append' is about concatenating sequences to
return a list sequence.

Oops.  Except that it's not.  Although it always
returns a list, in the general sense, it's not
always a sequence (a true list):

(append '(x y) [z]) => (x y . [z])

The devil is in the details.  Lisp is in many
ways an ad hoc language.  Some things are ugly.
Some things are elegant.  Some things are ugly
AND elegant.  Complicated - and simple.