rust/src/libstd/util.rs

/*
Module: util
*/

/*
Function: id

The identity function
*/
pure fn id<T: copy>(x: T) -> T { x }

/*
Function: unreachable

A standard function to use to indicate unreachable code. Because the
function is guaranteed to fail typestate will correctly identify
any code paths following the appearance of this function as unreachable.
*/
fn unreachable() -> ! {
    fail "Internal error: entered unreachable code";
}

/* FIXME (issue #141):  See test/run-pass/constrained-type.rs.  Uncomment
 * the constraint once fixed. */
/*
Function: rational

A rational number
*/
type rational = {num: int, den: int}; // : int::positive(*.den);

/*
Function: rational_leq
*/
pure fn rational_leq(x: rational, y: rational) -> bool {
    // NB: Uses the fact that rationals have positive denominators WLOG:

    x.num * y.den <= y.num * x.den
}

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