Splitting this from the colour thread(https://forum.dlang.org/thread/mailman.961.1475765646.2994.digitalmars-d@puremagic.com?page=1).

So currently D does not have a way to express batch operations that work seamlessly with normal ranges.

Manu suggested to use the array operation syntax. I suggest something along the lines of the following, forwarding any operations to the static array.

struct InBatchesOfN(size_t N,R) if( N!=0 && isInputRange!R
                                                             && hasLength!R)
{
    R r;
    static struct Batch
    {
        ElementType!(R)[N] elements;
        auto get() { return elements[]; }
        alias get this;
        Batch opBinary(string op)(Batch rhs) if(hasOperator!(ElementType!(R),op))
        {
            Batch b;
            foreach(i; iota(N)) mixin("b.elements[i] = elememts[i] "~op~" rhs.elements[i]");
            return b;
        }
        //repeat for opUnary,opOpAssign,opDispatch etc...
    }
    Batch batch;
    this(R _r)
    {
        // could have overloads where undefined elements == ElementType!(R).init
        assert(_r.length % N ==0);
        r = _r;
        foreach( i; iota(N))
        {
            batch[i] = r.front;
            r.popFront;
        }
    }
    bool empty() { return r.empty; }
    auto front() { return batch; }
    void popFront()
    {
        foreach(i; iota(N))
        {
            batch.elements[i] = r.front;
            r.popFront;
        }
    }
}

auto inBatchesOf(size_t N,R)(R r)
{
    return InBatchesOfN(r);
}

Thoughts?

On Tuesday, 11 October 2016 at 03:05:12 UTC, Nicholas Wilson wrote:
> Splitting this from the colour thread(https://forum.dlang.org/thread/mailman.961.1475765646.2994.digitalmars-d@puremagic.com?page=1).
>
> [...]

This will bloat like hell.
The best way would be to provide special Range-Definitions for those.
Such as
T[4] Front4 ()
or popFront4

On 11/10/2016 4:20 PM, Stefan Koch wrote:
> On Tuesday, 11 October 2016 at 03:05:12 UTC, Nicholas Wilson wrote:
>> Splitting this from the colour
>> thread(https://forum.dlang.org/thread/mailman.961.1475765646.2994.digitalmars-d@puremagic.com?page=1).
>>
>>
>> [...]
>
> This will bloat like hell.
> The best way would be to provide special Range-Definitions for those.
> Such as
> T[4] Front4 ()
> or popFront4

We would also want 2, 8 and 16 for SIMD reasons.

On Tuesday, 11 October 2016 at 03:20:54 UTC, Stefan Koch wrote:
> On Tuesday, 11 October 2016 at 03:05:12 UTC, Nicholas Wilson wrote:
>> Splitting this from the colour thread(https://forum.dlang.org/thread/mailman.961.1475765646.2994.digitalmars-d@puremagic.com?page=1).
>>
>> [...]
>
> This will bloat like hell.
> The best way would be to provide special Range-Definitions for those.
> Such as
> T[4] Front4 ()
> or popFront4

It will be possible to have an overload for ranges that have slicing, that copies in chunks.