Macro rust_io

macro_rules! rust_io {
    (yield $r:expr ;) => { ... };
    (let $p:pat = $e:expr ; $($r:tt)*) => { ... };
    (_ <- $x:expr ; $($r:tt)*) => { ... };
    ($bind:ident <- $x:expr ; $($r:tt)*) => { ... };
    ($a:expr) => { ... };
}

Macro implementation for rust_io defining several operators to be used emulating Haskel [do notation] Work based on original idea of crate [do-notation]