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digitalmars.D.learn - parallel foreach

reply Alex <sascha.orlov gmail.com> writes:
Hi all,
the last foreach in the following code does not compile... Is 
this a bug, or is something wrong with my syntax?

void main()
{
	import std.parallelism : parallel;
	import std.range : iota;
	
	foreach(i; iota(0, 5)){}
	foreach(i; staticIota!(0, 5)){}
	foreach(i; parallel(iota(0, 5))){}
	foreach(i; parallel(staticIota!(0, 5))){}
}

// copied from core.internal.traits
template staticIota(int beg, int end)
{
	import std.typetuple;
     static if (beg + 1 >= end)
     {
         static if (beg >= end)
         {
             alias staticIota = TypeTuple!();
         }
         else
         {
             alias staticIota = TypeTuple!(+beg);
         }
     }
     else
     {
         enum mid = beg + (end - beg) / 2;
         alias staticIota = TypeTuple!(staticIota!(beg, mid), 
staticIota!(mid, end));
     }
}
May 01 2017
parent reply Nicholas Wilson <iamthewilsonator hotmail.com> writes:
On Monday, 1 May 2017 at 12:42:01 UTC, Alex wrote:

 Hi all,
 the last foreach in the following code does not compile... Is 
 this a bug, or is something wrong with my syntax?

 void main()
 {
 	import std.parallelism : parallel;
 	import std.range : iota;
 	
 	foreach(i; iota(0, 5)){}
 	foreach(i; staticIota!(0, 5)){}
 	foreach(i; parallel(iota(0, 5))){}
 	foreach(i; parallel(staticIota!(0, 5))){}
 }

 // copied from core.internal.traits
 template staticIota(int beg, int end)
 {
 	import std.typetuple;
     static if (beg + 1 >= end)
     {
         static if (beg >= end)
         {
             alias staticIota = TypeTuple!();
         }
         else
         {
             alias staticIota = TypeTuple!(+beg);
         }
     }
     else
     {
         enum mid = beg + (end - beg) / 2;
         alias staticIota = TypeTuple!(staticIota!(beg, mid), 
 staticIota!(mid, end));
     }
 }


Because staticIota expands to 0,1,2,3,4
so you are trying todo
foreach(i; parallel(0,1,2,3,4){}
which doesn't work.
try
foreach(i; parallel([staticIota!(0, 5)])){}
or
foreach(i; parallel(only(staticIota!(0, 5)))){}
not sure of the second one will work.
May 01 2017
parent Alex <sascha.orlov gmail.com> writes:
On Monday, 1 May 2017 at 13:24:55 UTC, Nicholas Wilson wrote:

 Because staticIota expands to 0,1,2,3,4
 so you are trying todo
 foreach(i; parallel(0,1,2,3,4){}
 which doesn't work.
 try
 foreach(i; parallel([staticIota!(0, 5)])){}
 or
 foreach(i; parallel(only(staticIota!(0, 5)))){}
 not sure of the second one will work.


Ah thanks. Both versions work.
May 01 2017