type EnvMap = TreeMap<String Decorated Decl>; type Set<a> = [a];
Transparent type aliases can be declared as follows:
type Name < type variables... > = type;
Please note these are aliases, not actual new types. For that see nonterminal declarations.
newtype declares an opaque type alias, meaning the new type name is not transparently equal to what it wraps.
Instead, the type must be explicitly wrapped and unwrapped.
Silver has no support for this yet, other than emulating it by using a nonterminal and production.