merging map/filter/reduce/... in D

[cym13 via Digitalmars-d-learn]

On Friday, 29 January 2016 at 08:06:14 UTC, glathoud wrote:
> Thanks. I am glad be wrong on that one.
>
> I had a look at map & filter in the source code ; pleased to 
> see they're lazily implemented!
>
> map
> https://github.com/D-Programming-Language/phobos/blob/master/std/algorithm/iteration.d#L425
>
> filter
> https://github.com/D-Programming-Language/phobos/blob/master/std/algorithm/iteration.d#L924
> I had to look for FilterResult!
> https://github.com/D-Programming-Language/phobos/blob/master/std/algorithm/iteration.d#L979
>
> Small remark: One could make the laziness of filter a bit more 
> clear in the doc though - at least for newbies like me.
> http://dlang.org/phobos/std_algorithm_iteration.html
>
> Best regards,
> Guillaume

While it's not entirely true because one can implement a non-lazy 
range, any time you see the word "range" in the documentation you 
should think that it is lazy. Ranges are an important concept in 
D so we usually don't bother explaining it in the doc. You can 
read about it here if you need to: 
http://ddili.org/ders/d.en/ranges.html and 
http://dlang.org/phobos/std_range.html