33 lines
633 B
Rust
33 lines
633 B
Rust
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enum ast& {
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num(uint),
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add(&ast, &ast)
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}
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fn build() {
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let x = num(3u);
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let y = num(4u);
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let z = add(&x, &y);
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compute(&z);
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}
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fn compute(x: &ast) -> uint {
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alt *x {
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num(x) { x }
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add(x, y) { compute(x) + compute(y) }
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}
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}
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fn map_nums(x: &ast, f: fn(uint) -> uint) -> &ast {
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alt *x {
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num(x) {
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ret &num(f(x)); //! ERROR mismatched types: expected `&ast/&` but found
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}
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add(x, y) {
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let m_x = map_nums(x, f);
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let m_y = map_nums(y, f);
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ret &add(m_x, m_y); //! ERROR mismatched types: expected `&ast/&` but found
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}
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}
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}
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fn main() {}
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