53 lines
1.5 KiB
Rust
53 lines
1.5 KiB
Rust
// Check usage and precedence of block arguments in expressions:
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fn main() {
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let v = ~[-1f, 0f, 1f, 2f, 3f];
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// Statement form does not require parentheses:
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do vec::iter(v) |i| {
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log(info, i);
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}
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// Usable at all:
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let mut any_negative = do vec::any(v) |e| { float::is_negative(e) };
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assert any_negative;
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// Higher precedence than assignments:
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any_negative = do vec::any(v) |e| { float::is_negative(e) };
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assert any_negative;
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// Higher precedence than unary operations:
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let abs_v = do vec::map(v) |e| { float::abs(e) };
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assert do vec::all(abs_v) |e| { float::is_nonnegative(e) };
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assert !do vec::any(abs_v) |e| { float::is_negative(e) };
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// Usable in funny statement-like forms:
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if !do vec::any(v) |e| { float::is_positive(e) } {
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assert false;
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}
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match do vec::all(v) |e| { float::is_negative(e) } {
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true => { fail ~"incorrect answer."; }
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false => { }
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}
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match 3 {
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_ if do vec::any(v) |e| { float::is_negative(e) } => {
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}
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_ => {
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fail ~"wrong answer.";
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}
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}
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// Lower precedence than binary operations:
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let w = do vec::foldl(0f, v) |x, y| { x + y } + 10f;
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let y = do vec::foldl(0f, v) |x, y| { x + y } + 10f;
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let z = 10f + do vec::foldl(0f, v) |x, y| { x + y };
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assert w == y;
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assert y == z;
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// In the tail of a block
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let w =
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if true { do vec::any(abs_v) |e| { float::is_nonnegative(e) } }
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else { false };
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assert w;
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}
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