I dun a DIP, possibly the best DIP ever

[Manu]

On Fri, Apr 24, 2020 at 6:40 PM Walter Bright via Digitalmars-d <
digitalmars-d at puremagic.com> wrote:

> On 4/24/2020 1:24 AM, Walter Bright wrote:
> > On 4/23/2020 11:00 PM, Manu wrote:
> >> I guess this is the key case you need to solve for:
> >>
> >>    template T(Args...) {}
> >>    T!(Tup)     -> T!(0, 1, 2)
> >>    T!(Tup)...  -> T!0, T!1, T!2
> >>
> >> And the parallel expansion disambiguation is also critical:
> >>    T!(Tup, Tup2...)...  -> T!(0, 3, 4, 5), T!(1, 3, 4, 5), T!(2, 3, 4,
> 5)
> >>
> >> If you can solve those, the rest will probably follow.
> >
> > Fair enough. Though there needs to be a rationale as to why those two
> particuler
> > cases are needed and critical.
>
> Please keep in mind that the following works today:
>
>    void foo(int);
>
>    template tuple(T...) { enum tuple = T; }
>
>    void test() {
>      auto t = tuple!(1, 2, 3);
>      static foreach (i, e; t)
>          foo(e + i);
>    }
>
> and generates:
>
>    void test() {
>       foo(1); foo(3); foo(5);
>    }
>

static foreach is not an expression, and it's very hard to involve those
result calls in some conjunction. Expand that code to || them together...
it gets ugly real fast.
I wouldn't have wasted my time writing this DIP and a reference
implementation if static foreach was fine.

Find instances of `staticMap` in phobos and/or user code, and show how you
can replace them with static foreach, then there's something to talk about.
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