v/examples/tree_of_nodes.v

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type Tree = Empty | Node
struct Empty {}
struct Node {
value int
left Tree
right Tree
}
// NB: a match expression, infers the type of its result
// from the type of the return value in the first branch,
// => it needs an explicit int(0) cast here:
fn size(tree Tree) int {
return match tree {
Empty { int(0) }
Node { 1 + size(tree.left) + size(tree.right) }
}
}
fn main() {
node1 := Node{30, Empty{}, Empty{}}
node2 := Node{20, Empty{}, Empty{}}
tree := Node{10, node1, node2}
println('tree structure:\n $tree')
println('tree size: ${size(tree)}')
}