Feedback on a typing design (patterns library)

Sciss · November 7, 2017, 1:07pm

Hi there,

I have started playing with design ideas about porting part of SuperCollider’s pattern library to Scala. For those not familiar with it, it is a sort of stream/iterator processing, but in a dynamically typed language, allowing you to do wild things and mix different types. So I’m still undecided whether I’m going to introduce a bit of static type constraints or not. Take for example this pattern:

x = Pseq([[3.0, 4.0], 5.0], 3) + 5
x.asStream.all  // [ [ 8, 9 ], 10, [ 8, 9 ], 10, [ 8, 9 ], 10 ]

which would be allowed in SuperCollider.

I’m looking at a meaningful subset of these operations. Here is an attempt to model the pattern elements (Elem) with types:

github.com

Sciss/Patterns/blob/3b8e67c97c6b4082864f64f016a30dd30b6b510f/src/main/scala/de/sciss/patterns/Types.scala

package de.sciss.patterns

import scala.collection.AbstractIterator
import scala.language.implicitConversions

object Types {
  def main(args: Array[String]): Unit = example()

  trait Top {
    type Out
  }

  trait Bridge[T1 <: Top, T2 <: Top, T <: Top] {
    val tpe: T

    def lift1(a: T1#Out): tpe.Out
    def lift2(a: T2#Out): tpe.Out
  }

//  implicit def idBridge[T <: Top](implicit tpe: T): Bridge[T, T, T] = new IdBridge[T](tpe)

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Any feedback would be appreciated.

best, .h.h.