Macro defmac 

macro_rules! defmac {
    (@nest $name:ident ($dol:tt) => (
        [$($arg:ident)*] $($result_body:tt)+)
    ) => { ... };
    (@nest $name:ident ($dol:tt) => (
            [$($arg:ident)*] $($result_body:tt)+
        )
        $p1:pat $(, $p2:pat)*
    ) => { ... };
    (@revpats [$($args:tt)*] [$($pr:pat),*]) => { ... };
    (@revpats [$($args:tt)*] [$($pr:pat),*] $p1:pat $(, $p2:pat)*) => { ... };
    ($name:ident $($p1:pat),* => $result:expr) => { ... };
}

A macro to define lambda-like macros inline.

Syntax:

defmac!( name [ pattern [, pattern … ]] => expression )

name is the name of the new macro, followed by 0 or more patterns separated by comma. A pattern can be just an argument name like x or a pattern like ref value, (x, y) etc.

Supports arbitrary many arguments.