Macro fp_rust::do_m_pattern

macro_rules! do_m_pattern {
    (
        let $p:pat = $e:expr ; $( $t:tt )*
    ) => { ... };
    (
        let $p:ident : $ty:ty = $e:expr ; $( $t:tt )*
    ) => { ... };
    (
        let mut $p:ident : $ty:ty = $e:expr ; $( $t:tt )*
    ) => { ... };
    (
        $p:ident = $e:expr ; $( $t:tt )*
    ) => { ... };
    (
        exec $b:expr ; $( $t:tt )*
    ) => { ... };
    (
        ret $e:expr
    ) => { ... };
    ($p:ident $ty:ty, $val:expr, yield_from $cor:expr; $($t:tt)*) => { ... };
}

Run codes inside a doM block(Haskell do notation) (this is a sync macro)