[Issue 8467] New: A different third signature for std.algorithm.count

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=8467

           Summary: A different third signature for std.algorithm.count
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: Phobos
        AssignedTo: nobody at puremagic.com
        ReportedBy: bearophile_hugs at eml.cc


--- Comment #0 from bearophile_hugs at eml.cc 2012-07-29 19:33:55 PDT ---
The third signature of std.algorithm.count() is:
http://dlang.org/phobos/std_algorithm.html#count

size_t count(alias pred = "true", Range)(Range r);


So this program is equivalent to using walkLength, and in my opinion this is
not so useful:

import std.algorithm: count;
void main() {
    assert(count([0, 0, 1]) == 3);
}


I think a more useful default for that third form is something similar to:

size_t count(alias pred = "a", Range)(Range r);


So it counts the true values:

import std.algorithm: count;
void main() {
    assert(count([0, 0, 1]) == 1);
}


But keep in mind that unlike Python in D even empty arrays are sometimes
"true", etc:

import std.algorithm: count;
void main() {
    assert(count!"a"([(new int[1])[0..0]]) == 1);
}

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