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digitalmars.D.bugs - [Issue 3377] New: [tdpl] static foreach should be implemented

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=3377

           Summary: [tdpl] static foreach should be implemented
           Product: D
           Version: unspecified
          Platform: Other
        OS/Version: Linux
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: DMD
        AssignedTo: nobody puremagic.com
        ReportedBy: andrei metalanguage.com


--- Comment #0 from Andrei Alexandrescu <andrei metalanguage.com> 2009-10-08
12:12:29 PDT ---
This should compile:

import std.contracts;

double unrolledDotProduct(double[] a, double[] b) {
   enum branches = 4;
   enforce(a.length == b.length);
   double result = 0;
   auto n = (a.length / branches) * branches;
   double temp[branches];
   for (size_t i = 0; i != n; i += branches) {
      static foreach (j ; 0 .. branches) {
         temp[j] = a[i + j] * b[i + j];
      }
      result += inline_sum(temp);
   }
   foreach (j; n .. a.length) {
      result += a[j] * b[j];
   }
   return result;
}

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Oct 08 2009
next sibling parent reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=3377


downs <default_357-line yahoo.de> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |default_357-line yahoo.de


--- Comment #1 from downs <default_357-line yahoo.de> 2009-10-08 12:35:53 PDT
---
This does compile (on 1.0):

template Repeat(T, int I) {
  static if (!I) alias Tuple!() Repeat;
  else alias Tuple!(T, Repeat!(T, I - 1)) Repeat;
}

double unrolledDotProduct(double[] a, double[] b) {
   const branches = 4;
   assert(a.length == b.length);
   double result = 0;
   auto n = (a.length / branches) * branches;
   double temp[branches];
   for (size_t i = 0; i != n; i += branches) {
      foreach (j, BOGUS; Repeat!(void, branches)) {
         temp[j] = a[i + j] * b[i + j];
      }
      result += inline_sum(temp);
   }
   foreach (j; n .. a.length) {
      result += a[j] * b[j];
   }
   return result;
}

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Oct 08 2009
parent Christopher Wright <dhasenan gmail.com> writes:
d-bugmail puremagic.com wrote:
 http://d.puremagic.com/issues/show_bug.cgi?id=3377
 
 
 downs <default_357-line yahoo.de> changed:
 
            What    |Removed                     |Added
 ----------------------------------------------------------------------------
                  CC|                            |default_357-line yahoo.de
 
 
 --- Comment #1 from downs <default_357-line yahoo.de> 2009-10-08 12:35:53 PDT
---
 This does compile (on 1.0):
 
 template Repeat(T, int I) {
   static if (!I) alias Tuple!() Repeat;
   else alias Tuple!(T, Repeat!(T, I - 1)) Repeat;
 }

downs, you are a genius. You can create code that is both elegant and dreadful. You make the world a more interesting place.
Oct 08 2009
prev sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=3377


Walter Bright <bugzilla digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |bugzilla digitalmars.com
         Resolution|                            |WONTFIX


--- Comment #2 from Walter Bright <bugzilla digitalmars.com> 2009-11-18
13:38:27 PST ---
Many problems have come up with the design of this, so will mark as won't
implement until a thorough design is developed.

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Nov 18 2009