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.
