Macro make_context_ty

macro_rules! make_context_ty {
    ($context_name:ident, $empty_context_name:ident, $type:ty $(, $types:ty)* $(,)* ) => { ... };
    ($context_name:ident, $empty_context_name:ident $(,)* ) => { ... };
}

Macro for easily defining context types. The first argument should be a context type created with new_context_type! and subsequent arguments are the types to be stored in the context, with the outermost first.

// the following two types are identical
type ExampleContext1 = make_context_ty!(MyContext, MyEmptyContext, Type1, Type2, Type3);
type ExampleContext2 = MyContext<Type1, MyContext<Type2, MyContext<Type3, MyEmptyContext>>>;

// e.g. this wouldn't compile if they were different types
fn do_nothing(input: ExampleContext1) -> ExampleContext2 {
    input
}