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