Set#map Deduping and Possibly Unsafe Behavior

zorba128 · December 19, 2023, 6:48am

I’d like to propose slightly different approach to solve this otherwise unsolvable problem.
Please take a look at issue I posted recently:

Code snippet showing how it addresses problem described at the beginning of this discussion:

github.com

zorba128/scala-collection-strict/blob/master/src/test/scala/io/mk/collections/ScalaIssue11580.scala

package io.mk.collections

import org.scalatest.funsuite.AnyFunSuite

/** Shows how proposed approach solves `https://github.com/scala/bug/issues/11580`.
 */
class ScalaIssue11580 extends AnyFunSuite {
  test("StrictCollections") {
    val elements = StrictSet(1, 2, 3)
    val weights = StrictMap(1 -> 1.0, 2 -> 1.0, 3 -> 1.0)
    val values = StrictMap(1 -> 0.5, 2 -> 0.5, 3 -> 0.5)

    // Element 0.5 already exists.
    intercept[IllegalArgumentException] {
      val wSum = elements.map { element =>
        weights(element) * values(element)
      }.sum
      assert(wSum == 1.5)
    }
  }

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m.