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// Sums all nodes of a binary tree, recursively.
#include <metalang99.h>
#define leaf(x) ML99_choice(v(leaf), x)
#define node(lhs, data, rhs) ML99_choice(v(node), lhs, data, rhs)
#define sumTree(tree) ML99_match(tree, v(sumTree_))
#define sumTree_leaf_IMPL(x) v(x)
#define sumTree_node_IMPL(lhs, data, rhs) ML99_add3(sumTree(v(lhs)), v(data), sumTree(v(rhs)))
/*
* 4
* / \
* / \
* / \
* 2 6
* / \ / \
* 1 3 5 7
*/
#define TREE node(node(leaf(v(1)), v(2), leaf(v(3))), v(4), node(leaf(v(5)), v(6), leaf(v(7))))
ML99_ASSERT_EQ(sumTree(TREE), v(28));
int main(void) {}
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