Macro tract_core::element_wise

macro_rules! element_wise {
    ($func:ident, $Op:ident $({$($var: ident : $var_typ: path),*})?,
        $( [$($typ:ident),*] => $f:expr ),*
        $(; cost: $cost:expr )?
        $(; prefix: $prefix:expr )?
        $(; validation: $validation:expr )?
    ) => { ... };
}