Why is std.algorithm so complicated to use?

[Andrei Alexandrescu]

On 7/10/12 11:17 AM, Jonathan M Davis wrote:
> On Tuesday, July 10, 2012 10:21:23 Andrei Alexandrescu wrote:
>> On 7/10/12 5:35 AM, Jacob Carlborg wrote:
>>> On 2012-07-10 08:59, Dmitry Olshansky wrote:
>>>> Can you do it in other languages?
>>>
>>> Sure, in Ruby, but that only works on arrays:
>>>
>>> p [5, 3, 5, 6, 8].uniq.map{ |e| e.to_s }.sort
>>
>> This is very inefficient.
>>
>> I agree that if efficiency wasn't a concern for std.algorithm, its API
>> would have been different. As things are, I think std.algorithm strikes
>> a very good balance between efficiency and usability.
>
> The other thing that affects a lot is infinite ranges. The functions with lazy
> results work wonderfully with infinite ranges but would generally result in
> infinite loops if used with functions with eager results.
>
> auto vals = map!"a % 10"(rndGen());
>
> works great, but you'd be forced to use take directly on rndGen pretty much
> all the time you wanted to do something like that if functions like map were
> lazy.
>
> But I suspect that the sort of people who will be complaining about map not
> returning an array are also the sort of people who won't be all that familar
> with operating on infinite lists and at least initially probably won't care.
>
> - Jonathan M Davis

It's also about the unnecessary work done eagerly on finite but long inputs.

Andrei