Nested match structures are difficult to understand because you can easily confuse the cases of an inner match as belonging to an outer statement. Therefore nested match statements should be avoided.

Specifically, you should structure your code to avoid the need for nested match statements, but if you cannot, then consider moving the inner match to another function.

Noncompliant Code Example

def foo(n: Int, m: Int): Unit = {
  n match {
    case 0 => m match {
        case 0 =>
        // ...
      }
    case 1 =>
    // ...
  }
}

Compliant Solution

def foo(n: Int, m: Int): Unit = {
  n match {
    case 0 => bar(m)
    case 1 =>
    // ...
  }
}

def bar(m: Int): Unit = {
  m match {
    case 0 =>
    // ...
  }
}