Hyperlinked twins of code repositories (developed since 2023) are websites that support precise name-based code navigation using ordinary web browsers.
The MSOS in Prolog project (2002–2004) illustrates how MSOS rules for the dynamic semantics of a simple imperative programming language can be written as Prolog clauses.
The Action Environment (2001-2005) was a prototype tool that supported use of so-called constructive action semantics (a hybrid of action semantics and component-based semantics).