bug#29489: Obsolete gnus-remove-if and gnus-remove-if-not

[Noam Postavsky]

Eric Abrahamsen <eric@ericabrahamsen.net> writes:

>> Although the docstring claims "hash table", while the code says...
>>
>>> -    (if hash-table-p
>>> -   (mapatoms (lambda (symbol)
>>> -               (unless (funcall predicate symbol)
>>> -                 (push symbol out)))
>>> -             sequence)
>>
>> obarray?
>
> Shhh, that's my next patch to Gnus! Turning its "hash tables" into
> actual hash tables. The obarrays are an impressive and horrible hack.
>
> For this version of the patch, `seq-filter' works on vectors. In the
> next patch, it's replaced by seq-filter->map-keys.

Hmm, seq-filter works on vectors, but it's not reliable for obarrays:

    (let ((list nil)
          (ob (make-vector 3 0)))
      (intern "foo" ob)
      (intern "bar" ob)
      (intern "xxx" ob)
      (seq-filter (lambda (_) t) ob)) ;=> (xxx 0 0)