bug#42323: 26.3; Doc string of `seq-map'

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

C-h f seq-map

___

 seq-map is a compiled Lisp function in 'seq.el'.

 (seq-map FUNCTION SEQUENCE)

 Return the result of applying FUNCTION to each element of SEQUENCE.

 This is a generic function.

 Implementations:

 (function (sequence sequence)) in 'seq.el'.

 Undocumented

 (function sequence) in 'seq.el'.

 Undocumented
___

This doc doesn't stand on its own at all, beyond the first line.  It
doesn't look other Emacs doc strings.  It reads like some text generated
primitively by computer, with no real care about readers/users.

You can't have a clue about what "Implementations:" means, or the
individual implementation descriptions mean, unless you know about
`cl-defgeneric' and `cl-defmethod'.

At the very least there should be some link to the doc of those, or
(preferably) a description of what's involved by saying "This is a
generic function" - IF that's really necessary to understanding
`seq-map'.

Elisp users shouldn't be expected to be proficient in Common Lisp.  They
should be able to use and understand a function such as `seq-map'
without caring about its implementation.  seq.el constructs should be
describable and described on their own, ideally without requiring users
to dig into Common Lisp constructs.

Or IF understanding the implementation is really necessary, then the
fact that seq.el is implemented using cl constructs can't be elided.  Is
that really the case?  What we have now is a pretty useless, and quite
confusing, indirect/implicit reference to a cl implementation.  Why?
How is that helpful?


In GNU Emacs 26.3 (build 1, x86_64-w64-mingw32)
 of 2019-08-29
Repository revision: 96dd0196c28bc36779584e47fffcca433c9309cd
Windowing system distributor `Microsoft Corp.', version 10.0.18362
Configured using:
 `configure --without-dbus --host=x86_64-w64-mingw32
 --without-compress-install 'CFLAGS=-O2 -static -g3''