PlusCal

PlusCal (formerly called +CAL) is a formal specification language created by Leslie Lamport, which transpiles to TLA⁺. In contrast to TLA⁺'s action-oriented focus on distributed systems, PlusCal most resembles an imperative programming language and is better-suited to specifying sequential algorithms. PlusCal was designed to replace pseudocode, retaining its simplicity while providing a formally-defined and verifiable language. A one-bit clock is written in PlusCal as follows:

PlusCal tools and documentation are found on the PlusCal Algorithm Language page.