Scala: Ignore case class field for equals/hascode?

by

Only parameters in the first parameter section are considered for equality and hashing.

scala> case class Foo(a: Int)(b: Int)
defined class Foo

scala> Foo(0)(0) == Foo(0)(1)
res0: Boolean = true

scala> Seq(0, 1).map(Foo(0)(_).hashCode)
res1: Seq[Int] = List(-1669410282, -1669410282)

UPDATE

To expose b as a field:

scala> case class Foo(a: Int)(val b: Int)
defined class Foo

scala> Foo(0)(1).b
res3: Int = 1

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