Repeat and chunks

[Saurabh Das via Digitalmars-d-learn]

On Monday, 24 October 2016 at 15:28:50 UTC, Saurabh Das wrote:
> On Monday, 24 October 2016 at 14:25:46 UTC, Dorian Haglund 
> wrote:
>> Hey,
>>
>> The following code crashes with DMD64 D Compiler v2.071.2:
>>
>> import std.algorithm;
>> import std.stdio;
>> import std.range;
>>
>> int main()
>> {
>>   repeat(8, 10).chunks(3).writeln();
>>
>>   return 0;
>> }
>>
>> Error message:
>>
>> pure nothrow @nogc @safe 
>> std.range.Take!(std.range.Repeat!(int).Repeat).Take 
>> std.range.Repeat!(int).Repeat.opSlice(ulong, ulong)
>>
>> If I replace repeat with iota, or a literal range (like [1, 2 
>> ,3, 4]), I don't get the crash.
>>
>> I don't see why I should not be able to use chunks with repeat.
>> If some property of repeat's range is missing to use chunks, 
>> shouldn't I get an error message ?
>>
>> Am I missing something ?
>>
>> PS: the behavior has been reproduced on someone else computer.
>>
>> Cheers :)
>
> This works:
>
> repeat(8, 12).chunks(3).writeln;
>
> The documentation of 
> https://dlang.org/phobos/std_range.html#.chunks mentions 
> something about evenly divisible by chunkSize – perhaps that is 
> the cause of the assert fail. Not 100% sure why that's there 
> though.
>
> Thanks,
> Saurabh

Some more cases, perhaps someone more knowledgeable can help:

import std.algorithm;
import std.stdio;
import std.range;

int main()
{
     [8, 8, 8, 8, 8, 8].chunks(3).writeln; // prints [[8, 8, 8], 
[8, 8, 8]]
     repeat(8, 6).writeln;                 // prints [8, 8, 8, 8, 
8, 8]
     repeat(8, 6).chunks(3).writeln;       // prints [[8, 8, 8]]. 
Why?

     assert([8, 8, 8, 8, 8, 8] == repeat(8, 6).array); // Passes
     assert([8, 8, 8, 8, 8, 8].chunks(3).array == repeat(8, 
6).array.chunks(3).array); // Passes
     assert([8, 8, 8, 8, 8, 8].chunks(3).array == repeat(8, 
6).chunks(3).map!(a => a.array).array); // Fails

     return 0;
}