Pipes

Little library that I always ended up reimplementing for various projects. The idea is the define a unit of work as a pipe, which can be composed together to form small programs.

An example!

import pipes.Pipe

class Doubler extends Pipe[Int, Int] {
  def apply(i: Int) = i * 2 :: Nil
}

class ToStringer extends Pipe[AnyRef, String] {
  def apply(a: AnyRef) = a.toString :: Nil
}

class Repeater(times: Int) extends Pipe[String, String] {
  def apply(s: String) = s * i
}

object Main {
  def main(args: Array[String]): Unit {
    val pipe = new Doubler() | new ToStringer() | new Repeater(2)
    println(pipe(3))
  }
}

This should print out:

List("6", "6")

Some Implicits

Implicits live an pipes.Pipes._ so importing them will give you some goodies

scala> import pipes.Pipes._
import pipes.Pipes._

scala> val p = List(1, 2, 3) | ((x: Int) => x + 1 :: Nil)
p: pipes.Source[Int] = pipes.Source$$ana$1@12345

scala> p()
res1: Traversable[Int] = List(2, 3, 4)

scala> val evens = p | ((x: Int) => if(x % 2 == 0) x :: Nil else Nil)
p: pipes.Source[Int] = pipes.Source$$ana$1@67890

scala> evens()
res2: Traversable[Int] = List(2, 4)