Demos for type-safe equality with Scala implicits
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Demos for type-safe equality with Scala implicits.

The simplest approach gives you a type-safe yet unbalanced === equality operation:

scala> import name.heikoseeberger.demoequality._
import name.heikoseeberger.demoequality._

scala> import SimpleEquality._
import SimpleEquality._

scala> 123 === 666
res0: Boolean = false

scala> "a" === "a"
res1: Boolean = true

scala> 123 === "a"
<console>:14: error: type mismatch;
 found   : String("a")
 required: Int
              123 === "a"

scala> Seq(1, 2, 3) === List(1, 2, 3)
res3: Boolean = true

scala> List(1, 2, 3) === Seq(1, 2, 3)
<console>:17: error: type mismatch;
 found   : Seq[Int]
 required: List[Int]
              List(1, 2, 3) === Seq(1, 2, 3)

For type- or view-based balanced equality more information see my blog series "Implicits unchained – type-safe equality":

  • Part 1: simple yet unbalanced equality
  • Part 2: type-wise balanced equality
  • Part 3: view-wise balanced equality

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This code is open source software licensed under the Apache 2.0 License.