The code example at https://dlang.org/phobos/std_parallelism.html

containing:


import std.algorithm, std.parallelism, std.range;

void main() {
    immutable n = 1_000_000_000;
    immutable delta = 1.0 / n;

    real getTerm(int i)
    {
        immutable x = ( i - 0.5 ) * delta;
        return delta / ( 1.0 + x * x ) ;
    }

    immutable pi = 4.0 * taskPool.reduce!"a + b"(
        std.algorithm.map!getTerm(iota(n))
    );
}

fails to compile as

std/parallelism.d(2632,36): Error: function std.parallelism.TaskPool.reduce!"a + b".reduce!(MapResult!(getTerm, Result)).reduce cannot get frame pointer to D main

on Git master.

Why?

Is there a solution?

Not that I know of, https://github.com/dlang/phobos/pull/4399. I think std.parallelism was designed around a D feature that was more a bug than a feature. This bug/feature seamed to be fixed some years ago. But I'm not 100%, as this was before my time.

On Tuesday, 29 November 2016 at 12:09:32 UTC, Nordlöw wrote:

> Is there a solution?

I've reported the issue recently https://issues.dlang.org/show_bug.cgi?id=16705.

On Tuesday, 29 November 2016 at 12:09:32 UTC, Nordlöw wrote:
> The code example at https://dlang.org/phobos/std_parallelism.html
>
> containing:
>
>
> import std.algorithm, std.parallelism, std.range;
>
> void main() {
>     immutable n = 1_000_000_000;
>     immutable delta = 1.0 / n;
>
>     real getTerm(int i)
>     {
>         immutable x = ( i - 0.5 ) * delta;
>         return delta / ( 1.0 + x * x ) ;
>     }
>
>     immutable pi = 4.0 * taskPool.reduce!"a + b"(
>         std.algorithm.map!getTerm(iota(n))
>     );
> }
>
> fails to compile as
>
> std/parallelism.d(2632,36): Error: function std.parallelism.TaskPool.reduce!"a + b".reduce!(MapResult!(getTerm, Result)).reduce cannot get frame pointer to D main
>
> on Git master.
>
> Why?
>
> Is there a solution?

Define the function you want to call globally.
and not inside another function.

On Tuesday, 29 November 2016 at 12:49:53 UTC, Stefan Koch wrote:
> Define the function you want to call globally.
> and not inside another function.

Yes. You can also find a very detailed explanation here https://github.com/dlang/phobos/pull/4915#issuecomment-262484753.