Derive Macro Semigroup 

#[derive(Semigroup)]

Derive macro for Semigroup.

Implements Semigroup for a struct by combining each field componentwise.

Example

#[derive(Semigroup)]
struct Foo {
    a: i32,  // i32: Semigroup (addition)
    b: String,  // String: Semigroup (concatenation)
}