Charity – Categorical programming language (1998)
Summary
Charity is a historical categorical programming language described on its home/README page. The README presents Charity as a pure, lazy, higher-order functional language built around strong categorical datatypes (inductive and coinductive) with programs expressed via folds and unfolds, suitable for software development, language research, and verification. The page is an archival overview, last revised in December 1998, detailing its concepts and lineage.