6.4.1 Introduction

Pattern matching is the process of branching depending on a value matching given, possibly deep patterns. In Haxe, all pattern matching is done within a switch expression where the individual case expressions represent the patterns. Here we will explore the syntax for different patterns using this data structure as running example:

enum Tree<T> {
  Leaf(v:T);
  Node(l:Tree<T>, r:Tree<T>);
}

Some pattern matcher basics include:

• Patterns will always be matched from top to bottom.
• The topmost pattern that matches the input value has its expression executed.
• A _ pattern matches anything, so case _: is equal to default: