> Hey,

> I have been doing some benchmarks. So, I have found that elixir's *lc* at
> least as slow then erlang's original feature.
> There are some benchmarks:

>    - https://github.com/AZatvornitskiy/nodexs/blob/rc/test/erl.erl
>    - https://github.com/AZatvornitskiy/nodexs/blob/rc/test/ex.ex

> Just for notice ))

> P.S: On the other hands, you should spread your purpose, and roadmap in
> general.
> Stay well ))

> Thanks for the benchmarks.

> The reason this happens is because our list comprehensions consider
> everything in filters except false or nil to be true.
> So this additional check costs us a bit. We could certainly optimize this
> though, since operators (like < and >) and other BIFs are known to return
> just booleans, allowing us to skip this check, I just haven't got to this
> optimization stage (it surprises me that this check is causing all this
> difference though).

> On Saturday, July 21, 2012 10:22:05 PM UTC+2, Alex Zatvorskiy wrote:

>> Hey,

>> I have been doing some benchmarks. So, I have found that elixir's *lc*at least as slow then erlang's original feature.
>> There are some benchmarks:

>>    - https://github.com/**AZatvornitskiy/nodexs/blob/rc/**test/erl.erl<https://github.com/AZatvornitskiy/nodexs/blob/rc/test/erl.erl>
>>    - https://github.com/**AZatvornitskiy/nodexs/blob/rc/**test/ex.ex<https://github.com/AZatvornitskiy/nodexs/blob/rc/test/ex.ex>

>> Just for notice ))

>> P.S: On the other hands, you should spread your purpose, and roadmap in
>> general.
>> Stay well ))

> Hello Alex,

> I have pushed a commit to Elixir master that skips the conversion check if
> the expression is known to return a boolean:

> https://github.com/elixir-lang/elixir/commit/6a7602d974f13924a6db6a52...

> This brings Elixir's performance to the same level as Erlang's for such
> common comprehensions.

> Cheers!

> *
> José Valim
> www.plataformatec.com.br
> Founder and Lead Developer
> *

> On Sat, Jul 21, 2012 at 10:45 PM, José Valim <jose.va...@gmail.com> wrote:

>> Hello Alex,

>> Thanks for the benchmarks.

>> The reason this happens is because our list comprehensions consider
>> everything in filters except false or nil to be true.
>> So this additional check costs us a bit. We could certainly optimize this
>> though, since operators (like < and >) and other BIFs are known to return
>> just booleans, allowing us to skip this check, I just haven't got to this
>> optimization stage (it surprises me that this check is causing all this
>> difference though).

>> On Saturday, July 21, 2012 10:22:05 PM UTC+2, Alex Zatvorskiy wrote:

>>> Hey,

>>> I have been doing some benchmarks. So, I have found that elixir's *lc*at least as slow then erlang's original feature.
>>> There are some benchmarks:

>>>    - https://github.com/**AZatvornitskiy/nodexs/blob/rc/**test/erl.erl<https://github.com/AZatvornitskiy/nodexs/blob/rc/test/erl.erl>
>>>    - https://github.com/**AZatvornitskiy/nodexs/blob/rc/**test/ex.ex<https://github.com/AZatvornitskiy/nodexs/blob/rc/test/ex.ex>

>>> Just for notice ))

>>> P.S: On the other hands, you should spread your purpose, and roadmap in
>>> general.
>>> Stay well ))