README.md

Beam

Purely functional streams, implemented with algebraic effects and handlers.

Data processing is done with entities such as Stream, Pipe and Sink, which can employ arbitrary sets of effects.

Optionally, they can be constructed as coroutines.

 

• ⚗️ 🔬 🧪   𝑷𝑹𝑶𝑻𝑶𝑻𝒀𝑷𝑬   🚧 WIP 🚧
• Uses Scala 3.
• Uses Turbolift as effect system.

 

Example

Stuttering Fibonacci sequence: when the number is even, emit it twice.

//> using scala "3.3.3"
//> using dep "io.github.marcinzh::beam-core:0.5.0"
import turbolift.!!
import turbolift.effects.Console
import beam._

@main def main =
  val fibos: Stream[Long, Any] =
    Stream.coroutine: fx =>
      def loop(a: Long, b: Long): Unit !! fx.type =
        for
          _ <- fx.write(a)
          _ <- !!.when(a % 2 == 0)(fx.write(a))
          _ <- loop(b, a + b)
        yield ()
      loop(1, 1)

  fibos.take(10).toVector
  .tapEff(xs => Console.println(xs.mkString(" ")))
  .handleWith(Console.handler)
  .unsafeRun