We should definitely optimize functions like at and random when we can, so definitely +1 on this front.
Regarding the other functions, I am still skeptical of their need. In particular, if we implement Enum.random fast enough for ranges, it would be enough to replace many of the other functions listed, like Integer.random and Range.random. :) *José Valim* www.plataformatec.com.br Skype: jv.ptec Founder and Director of R&D On Fri, Jun 24, 2016 at 12:21 AM, eksperimental <eksperimen...@autistici.org > wrote: > An answer from someone from the core team would be more than welcome on > this proposal. > > In addition to the proposed funtions, this proposal also tackles an issue > in Enum.random/1 when dealing with > a ranges, which is really slow if the range is huge, since it delegates > to take_random to be converted to a list to later pick one element. > > It optimized Enum.at/2 when dealing with ranges. > > Thank you. > > On Sat, 4 Jun 2016 08:37:19 +0700 > eksperimental <eksperimen...@autistici.org> wrote: > > > I forgot to mention that Range.at/3 has been implemented. > > > > *************** > > ### Range.at/3 > > > > It works the same way as Enum.at/3, but given a range, it returns an > > integer at the given `index`. > > > > This function is used to optimize `Enum.at/3` when dealing with > > ranges. *************** > > > > On Sat, 4 Jun 2016 08:18:21 +0700 > > eksperimental <eksperimen...@autistici.org> wrote: > > > > > You can read this proposal formated > > > https://github.com/eksperimental/experimental/blob/random/PROPOSAL.md > > > > > > # Introducing random related functions > > > > > > First I would like to address the need for implementing in Elixir > > > our function for generating random integers: `Integer.random/1` All > > > functions using random numbers, are calling > > > `:erlang.random_uniform/1`. This Erlang function is not zero based, > > > so there is an overhead to deal with it every time, adding and > > > subtracting (`:rand.uniform(n + 1) - 1`), thus leading to potential > > > bugs. > > > > > > > > > ## Integer module > > > > > > So my proposal is to add `Integer.random/1` and `Integer.random/2` > > > > > > - `Integer.random(limit)` - It returns a random integer from 0 to > > > limit (positive or negative integers) > > > > > > - `Integer.random(lower_limit, upper_limit)` - It returns a random > > > integer withing two limits. > > > > > > > > > ## Range module > > > > > > - `Range.random(range)` - It returns an integer within range. > > > - `Range.random(range, count)` - It returns an list of `count` > > > integers within range. count can be bigger than the range size. > > > > > > Uses cases: `Range.random/2` can be useful for generating charlists > > > of random chars within a range. It is also used by `Enum.random/2` > > > when the enumerable is a range. > > > > > > ## Enum module > > > > > > - `Enum.random(enumerable, count)` - It returns a list of count > > > size, of random items from enumerable. The main difference with > > > `Enum.take_random/2` is that latter will not include repeated > > > results, and if count is greater than the number of elements in > > > the enumerable, it will return short. So `Enum.random/2` guarantees > > > the count of items, and allows them to be repeated. > > > > > > `Enum.random/1` has been updated to not to call > > > `Enum.take_random/2`, but to use `Enum.at/3` instead. > > > > > > `Enum.at/3` has been optimized to use `Range.at/3` when the > > > enumerable is a range. > > > > > > > > > ## Additional functions implemented > > > > > > ### Integer.pad_random/2 > > > > > > If we are about to generate huge numbers, `:erlang.random_uniform/1` > > > will work to a certain limit. `Integer.pad_random/2` has fine tuning > > > options such as: > > > - force_size: true | false > > > - return: :integer | :positive | :negative | :zero_or_positive > > > | :zero_or_negative > > > > > > This list can generate incredible HUGE integers, in a very efficient > > > way. > > > > > > Use cases: benchmarking functions with different integers and data > > > size of specific length. > > > > > > ### Kernel.delta/2 and Range.delta/1 > > > > > > I took the chance and introduce new functions that helped me archive > > > random related functions listed above. > > > > > > - `Kernel.delta(number1, number2)`: It returns the absolute > > > difference between two numbers (integer or float). > > > - `Range.delta(range)`: It returns the absolute difference between > > > the range limits. > > > > > > It may sound simple, but I had made mistakes in the past > > > implementing a quick delta functions. > > > > > > > > > ## Implemented code > > > > > > It can be found here: > > > https://github.com/eksperimental/experimental/tree/random > > > > > > It can be cloned locally by running: > > > > > > $ git clone -b random --single-branch > > > https://github.com/eksperimental/experimental.git > > > > > > Looking forward to hearing your opinion, > > > > > > — Eksperimental > > > > > > > -- > You received this message because you are subscribed to the Google Groups > "elixir-lang-core" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to elixir-lang-core+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/elixir-lang-core/20160624052120.33c80adc.eksperimental%40autistici.org > . > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "elixir-lang-core" group. 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