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digitalmars.D.bugs - [Issue 5075] New: std.algorithm.map/filter don't support associative arrays or their byKey()/byValue()

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=5075

           Summary: std.algorithm.map/filter don't support associative
                    arrays or their byKey()/byValue()
           Product: D
           Version: D2
          Platform: x86
        OS/Version: Windows
            Status: NEW
          Keywords: rejects-valid
          Severity: normal
          Priority: P2
         Component: Phobos
        AssignedTo: nobody puremagic.com
        ReportedBy: bearophile_hugs eml.cc



This is a small interactive REPL with Python 2.6:



 data = {1:4, 2:3, 3:1, 4:0}
 map(lambda x: -x, data)






[-1, -2, -3, -4]

 filter(lambda x: x > 2, data)






[3, 4]


 from itertools import imap, ifilter
 list(imap(lambda x: -x, data))






[-1, -2, -3, -4]

 list(ifilter(lambda x: x > 2, data))






[3, 4]


'data' is an associative array, and "lambda" is used to define local anonymous
functions.

But map and filter in current Phobos with DMD 2.049 don't seem to support
associative arrays as inputs:


import std.algorithm: map, filter;
void main() {
    int[int] data = [1:4, 2:3, 3:1, 4:0];
    auto r1 = map!((int x) { return -x; })(data);
    auto r2 = filter!((int x) { return x > 2; })(data);
}


Nor byKey()/byValue():

import std.algorithm: map, filter;
void main() {
    int[int] data = [1:4, 2:3, 3:1, 4:0];
    auto r1 = map!((int x) { return -x; })(data.byKey());
    auto r2 = filter!((int x) { return x > 2; })(data.byKey());
    auto r3 = map!((int x) { return -x; })(data.byValue());
    auto r4 = filter!((int x) { return x > 2; })(data.byValue());    
}

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Oct 18 2010
next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=5075


kennytm gmail.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |kennytm gmail.com



See issue 4067.

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Oct 18 2010
prev sibling next sibling parent d-bugmail puremagic.com writes:
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 See issue 4067.


I mean issue 4607 :|.

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Oct 18 2010
prev sibling next sibling parent d-bugmail puremagic.com writes:
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Andrei Alexandrescu <andrei metalanguage.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
                 CC|                            |andrei metalanguage.com


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Oct 19 2010
prev sibling next sibling parent d-bugmail puremagic.com writes:
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So the second part of this bug report (about byKey()/byValue()) is a dupe. The
first part is an enhancement request that I think is not duplicated.

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Oct 19 2010
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=5075


bearophile_hugs eml.cc changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|std.algorithm.map/filter    |std.algorithm.map/filter
                   |don't support associative   |don't support associative
                   |arrays or their             |arrays
                   |byKey()/byValue()           |



After fixing issue 4607 this doesn't work still:


import std.algorithm: map, filter;
void main() {
    int[int] data = [1:4, 2:3, 3:1, 4:0];
    auto r1 = map!(x => -x)(data);
    auto r2 = filter!(x => x > 2)(data);
}


Also restricted the name of this issue.

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Jan 17 2012
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=5075


bearophile_hugs eml.cc changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |NEW


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Dec 06 2012
prev sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=5075


bearophile_hugs eml.cc changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |WONTFIX



Given the current design of Phobos, I think this enhancement request will not
be fulfilled. A future associativeArray.byPair that yields 2-tuples is a better
solution. So I close this down.

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Mar 30 2013