Use colon in macro definition

Is below macro possible to use colon in definition?

Foo:u8 = 2;
Bar: u16 = 20;


let Foo:u8 =2;
let Bar:u16=20;

I use ident for Foo and it does not allow colon

The purpose is a little unclear, and it makes the code harder to read IMO, but here you go:

macro_rules! impl_define {
    ($($i:ident : $t:ty = $e:expr ;)*) => {
            let $i: $t = $e;

Thanks, I should use ident instead of express for first item