| 1 | type Tree = Empty | Node |
| 2 | |
| 3 | struct Empty {} |
| 4 | |
| 5 | struct Node { |
| 6 | value int |
| 7 | left Tree |
| 8 | right Tree |
| 9 | } |
| 10 | |
| 11 | // Note: a match expression, infers the type of its result |
| 12 | // from the type of the return value in the first branch, |
| 13 | // => it needs an explicit int(0) cast here: |
| 14 | fn size(tree Tree) int { |
| 15 | return match tree { |
| 16 | Empty { int(0) } |
| 17 | Node { 1 + size(tree.left) + size(tree.right) } |
| 18 | } |
| 19 | } |
| 20 | |
| 21 | fn main() { |
| 22 | node1 := Node{30, Empty{}, Empty{}} |
| 23 | node2 := Node{20, Empty{}, Empty{}} |
| 24 | tree := Node{10, node1, node2} |
| 25 | println('tree structure:\n ${tree}') |
| 26 | println('tree size: ${size(tree)}') |
| 27 | } |
| 28 | |