Re: problems with Emacs 28

[Michael Heerdegen]

Emanuel Berg via Users list for the GNU Emacs text editor
<help-gnu-emacs@gnu.org> writes:

> The byte-compiler, and the docstring, tells me I should use `map-put!'
> as `map-put' is decrepated. However when I do that, I get a
> "map-not-inplace" error.

Yes, the replacement is not totally equivalent to the deprecated
function (if it would be, it would not make sense to introduce a
replacement at all).

If you read the docstring of `map-put!' you'll see why you get the
error.

You will probably rather want to use `setf' with an `alist-get' place
expression.  Yes, the recommendation was not a good one in your case.

> What is that bang (explication mark) syntax BTW?

That comes from the scheme tradition: it is used for functions that
modify something (state), unlike "pure" functions that "only" calculate
a return value.  E.g. `+', `car' vs. `setcar!' etc., you get it.

Regards,

Michael.