gistfile1.txt

package funsets

import common._

/**
 * 2. Purely Functional Sets.
 */
object FunSets {
  /**
   * We represent a set by its characteristic function, i.e.
   * its `contains` predicate.
   */
  type Set = Int => Boolean

  /**
   * Indicates whether a set contains a given element.
   */
  def contains(s: Set, elem: Int): Boolean = s(elem)

  /**
   * Returns the set of the one given element.
   */
  def singletonSet(elem: Int): Set = Set(elem)

  /**
   * Returns the union of the two given sets,
   * the sets of all elements that are in either `s` or `t`.
   */
  def union(s: Set, t: Set): Set = s | t

...
}


[info] Compiling 1 Scala source to /Volumes/Shared/personal_projects/functional_course/funsets/target/scala-2.10/classes...
[error] /Volumes/Shared/personal_projects/functional_course/funsets/src/main/scala/funsets/FunSets.scala:29: value | is not a member of Int => Boolean
[error]   def union(s: Set, t: Set): Set = s | t