vishal-h
Stream composition in Elixir
Let’s say we’ve a stream S1 that generates a random number between 1…100.
There is also another stream S2 that also generates a random number between 1…100.
Is it possible to compose S1 and S2 into another Stream S3 such that S3 emits if s1 + s2 is even? Functionality that I am looking for is similar to the one that is in RxJS.
I know the example is made up, but would like to know if streams in Elixir are composable.
Thanks!
Marked As Solved
Marcus
iex(63)> s1 = Stream.repeatedly(fn -> :rand.uniform(100) end)
#Function<54.33009823/2 in Stream.repeatedly/1>
iex(64)> s2 = Stream.repeatedly(fn -> :rand.uniform(100) end)
#Function<54.33009823/2 in Stream.repeatedly/1>
iex(65)> s3 = s1 |> Stream.zip(s2)
#Function<69.33009823/2 in Stream.zip/1>
iex(66)> s4 = Stream.map(s3, fn {a, b} -> a + b end)
#Stream<[
enum: #Function<69.33009823/2 in Stream.zip/1>,
funs: [#Function<49.33009823/1 in Stream.map/2>]
]>
iex(67)> s5 = Stream.filter(s4, fn x -> rem(x, 2) == 0 end)
#Stream<[
enum: #Function<69.33009823/2 in Stream.zip/1>,
funs: [#Function<49.33009823/1 in Stream.map/2>,
#Function<41.33009823/1 in Stream.filter/2>]
]>
iex(68)> Enum.take(s2, 5)
[31, 48, 21, 15, 7]
iex(69)> Enum.take(s3, 5)
[{97, 90}, {22, 37}, {11, 100}, {12, 44}, {24, 83}]
iex(71)> Enum.take(s4, 5)
[109, 62, 79, 105, 178]
iex(72)> Enum.take(s5, 5)
[144, 68, 34, 104, 50]
Also Liked
NobbZ
There are 2 means of composing streams, you can zip them or concatenate them.
Only of those makes sense in your case.
You can filter the resulting stream into another Stream.
Please take a look at
-
Stream.concat/2: https://hexdocs.pm/elixir/Stream.html#concat/2 -
Stream.zip/2: https://hexdocs.pm/elixir/Stream.html#zip/2 -
Stream.filter/2: https://hexdocs.pm/elixir/Stream.html#filter/2
Popular in Questions
Other popular topics
Latest on Elixir Forum
Sponsor Spotlight
Practical resources that improve the lives of professional developers. By developers, for developers.
Categories:
Sub Categories:
Forums
Our Sponsors
Build Elixir applications with speed and confidence.
Supporting innovation across the BEAM ecosystem.
We build reliable cloud platforms for business-critical systems.
Catch errors, track performance, monitor hosts and more.
Practical resources that improve the lives of professional developers.
Develop your skills with books, videos, and courses.
Enabling companies to succeed by building software people love.
Courses that'll move you from confusion to "Aha, now I get it!"