Basic Colections

Indexed Collection

Scalqa/Stream provides a general indexed collection - Idx, defined as following:

package scalqa

trait Idx[+A] extends Any {

  def size: Int

  def apply(idx: Int): A

  def all: ~[A]

Idx is functionally equivalent to scala.collections.IndexedSeq, but it is additionally specialized for primitives

For example, following calculations do not auto-box Int values and are 20 times faster compared to same done with IndexedSeq

val idx: Idx[Int] = (1 to 1000)[Idx]

var sum, i = 0

while(i < idx.size){ sum += idx(i); i+=1 }

println(sum == idx.all.sum)   // Prints true


Idx.Buffer is an Idx extension functionally equivalent to scala.collections.mutable.Buffer, but providing better growth performance for primitives


Idx.Immutable is a trait, which has following implementations: Refs, Bytes, Chars, Shorts, Ints, Longs, Floats, and Doubles

All these are an immutable Array wraps and their growth performance is on par with Array in general

Idx.Immutables could be the most efficient storage, consider following example:

val list: List[Int] = (1 to 1000000).toList

val ints: Ints      = (1 to 1000000).all.toRaw[Ints]

list holds 1 million objects of type List and 1 million objects of type java.lang.Integer. At conservative 16 bytes per object, this is 32Mb

ints holds a single object: Array[Int] of size = 1 million. At 4 bytes per Int, this is 4Mb

Not to mention that ints (in this particular case) were created over 10 times faster