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digitalmars.D.bugs - [Issue 8878] New: std.range is not pure

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=8878

           Summary: std.range is not pure
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Optlink
        AssignedTo: nobody puremagic.com
        ReportedBy: bioinfornatics gmail.com



05:27:40 PDT ---
Dear,

std.range should provide some pure function as;
iota -> 0 to to should give evey time the same result
zip  -> when it is an array (not an associative array) should be always the
same result

and other …

this missing feature allowed developers to use the pure in many case

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next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=8878


Jonathan M Davis <jmdavisProg gmx.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |jmdavisProg gmx.com
         Resolution|                            |WONTFIX



PDT ---
pure is inferred for templated functions. As long as the functions for the
range used are pure, then the functions in std.range and std.algorithm will
generally be pure. There may be some compiler bugs which make it so that that
doesn't always work like it's supposed to, but pretty much zero functions in
std.range and std.algorithm should be marked as pure, since whether they can be
pure or not really depends on the types used with them, which is why attribute
inferrence for templates was introduced in the first place.

If you have an issue with a specific function with a specific type which does
have pure member functions and the templated function is not being inferred as
pure, then please report it with an appropriate code sample, but it would be
wrong to specifically provide pure versions of functions like iota or zip.

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prev sibling next sibling parent d-bugmail puremagic.com writes:
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12:13:51 PDT ---
In first thanks jonathan to your answer.
Code below fail both when using pure with dmd/ldc  dmdfe 2.060 =>
http://dpaste.dzfl.pl/65efd36e

___________________________________________
import std.range;
import std.stdio;

pure uint square( in int[] x, in int[] y ){
    uint result = 0;
    foreach( item; zip( x, y ) )
        result += item[0] * item[1];
    return result;
}

int main(){
    int[3] a = [0,1,2];
    int[3] b = [1,2,3];
    writefln( "Square of %s with %s give %u", a, b, square( a, b ) );
}

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prev sibling next sibling parent d-bugmail puremagic.com writes:
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bearophile_hugs eml.cc changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bearophile_hugs eml.cc






 If you have an issue with a specific function with a specific type which does
 have pure member functions and the templated function is not being inferred as
 pure, then please report it with an appropriate code sample, but it would be
 wrong to specifically provide pure versions of functions like iota or zip.


This gives:
test.d(3): Error: pure function 'main' cannot call impure function 'iota'

import std.range: iota;
void main() pure {
    iota(10);
}




This gives:
test.d(4): Error: pure function 'main' cannot call impure function 'map'
test.d(4): Error: map is not nothrow
test.d(2): Error: function D main 'main' is nothrow yet may throw

import std.algorithm: map;
void main() pure nothrow {
    int[] data = [1, 2, 3];
    auto r = map!q{a * a}(data);
}


I propose to reopen this bug report, and change its meaning and title: instead
of asking for such functions to be marked as pure, to ask them to be usable in
a pure (and sometimes nothrow) situations.

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prev sibling next sibling parent d-bugmail puremagic.com writes:
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Jonathan M Davis <jmdavisProg gmx.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|Optlink                     |Phobos



PDT ---
It would probably be cleaner to just create a new bug report, but you can
reopen this one if you want to. Regardless, the bug as initially reported is
incorrect.

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prev sibling parent d-bugmail puremagic.com writes:
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bearophile_hugs eml.cc changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|Phobos                      |Optlink





 It would probably be cleaner to just create a new bug report,


Thank you for the answer. I have opened Issue 8882

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