Derive Macro JoinSemilattice 

#[derive(JoinSemilattice)]

Derive macro for JoinSemilattice.

Implements JoinSemilattice for a struct by joining each field componentwise.

Example

#[derive(JoinSemilattice)]
struct Foo {
    counter: Max<i32>,  // join = max
    tags: HashSet<String>,  // join = union
}