std.algorithm.searching: Implement none as shorthand for !any.

[FeepingCreature]

When any is invoked with a long condition in ufcs form, it can be a bit hard to read the logic, ie. if (!someArray.any!(element => someConditionTest(element) && element > 2)) - there's a lot of space between that negating ! and the actual test. In comparison, if (someArray.none!(element => someConditionTest(element) && element > 2)) is read more easily and quickly.

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[wilzbach]

Oh I understand your motivation and I do miss a few convenience functions myself from Phobos, but I'm not sure if @andralex will approve this.
-> Tagging him

As a recommendation, before making a PR to add new symbols it might be worthwhile to ask on Slack or the NG whether that could be controversial.
Or assume by default that adding a new symbol will be controversial :P

[wilzbach]

Auto-highlighting has been removed recently - _ is no longer necessary :)
dlang/dlang.org#2307

[wilzbach]

Auto-highlighting has been removed recently - _ is no longer necessary :)
dlang/dlang.org#2307

[wilzbach]

See_Also: $(LREF all), $(LREF none) ?

[andralex]

Indeed we don't do these kind of trivial functions - just compose using lambdas etc. Thanks!

[JackStouffer]

just compose using lambdas etc

In your own program you can do

alias none = x => !any(x);

void main()
{
    auto a = [0, 0, 0];
    assert(a.none);
}

Closing due to rejection.

[FeepingCreature]

Seems a bit silly to explicitly call out !any in the docs, even highlight it as none, and then not provide the natural verb for it.

And of course both any and all are just trivial wrappers around find...

[andralex]

Seems a bit silly to say in the docs "this is the same as none" and then not just providing none.

The relevant quote is: !any can be used to verify that none of the elements verify pred. That seems a reasonable thing to say. Clearly one could go on and define none as its own primitive - e.g. Ruby and Perl have unless as the negation of if.

Though of course, both any and all are just trivial wrappers around find.

Roger. There's been some decision making there, and one good argument was that range.find!(pred).empty was frequently needed and somewhat awkward.

[FeepingCreature]

In my opinion, the analogous reason for none is the distance between the verb and the negation if you're using UFCS, since you can't do expression.(!any). :) So either the negation ends up all the way at the start of the ufcs chain, ie. !foo.bar.baz.any!pred, possibly with newlines, or you have to write the awkward .all(!pred).

[WebFreak001]

boo! none is very common and when chaining calls and long lines it get's really confusing quickly