http://d.puremagic.com/issues/show_bug.cgi?id=7010

           Summary: Purity of map and filter
           Product: D
           Version: D2
          Platform: x86
        OS/Version: Windows
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: bearophile_hugs@eml.cc


--- Comment #0 from bearophile_hugs@eml.cc 2011-11-25 16:39:07 PST ---
There are some important cases where the purity inference of functions/delegates is not working well enough (DMD 2.057head):


import std.algorithm: map, filter;
int foo(immutable int x) pure nothrow {
    return 1;
}
void main() pure {
    immutable data = [1, 2, 3];
    auto m1 = map!((x){ return 1; })(data);     // OK
    auto m2 = map!((int x){ return 1; })(data); // OK
    auto m3 = map!q{ 1 }(data); // error, map is not pure
    auto m4 = map!foo(data);    // error, map is not pure
    //------------
    auto f1 = filter!((x){ return 1; })(data);     // OK
    auto f2 = filter!((int x){ return 1; })(data); // OK
    auto f3 = filter!q{ 1 }(data); // error, filter is not pure
    auto f4 = filter!foo(data);    // error, filter is not pure
}

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Kenji Hara <k.hara.pg@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|DMD                         |Phobos


--- Comment #1 from Kenji Hara <k.hara.pg@gmail.com> 2011-11-25 22:39:24 PST ---
The instantiation of map function given a delegate literal should not be
inferred as pure, it is compiler bug.
I've separated the issue into bug 7017.

Then this issue is now purely Phobos enhancement.

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hsteoh@quickfur.ath.cx changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |hsteoh@quickfur.ath.cx
         Resolution|                            |WORKSFORME


--- Comment #2 from hsteoh@quickfur.ath.cx 2013-07-09 09:01:21 PDT ---
This appears to have been fixed in git HEAD.

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