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 <[email protected]> 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 [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/elixir-lang-core/20160604083719.396e32e1.eksperimental%40autistici.org. For more options, visit https://groups.google.com/d/optout.
