Lean
An experimental language from the University of Nijmegen and University of East Anglia, based on graph rewriting and useful as an intermediate language. Lean is descended from Dactl0.
Clean is a subset of Lean.
["Towards an Intermediate Language Based on Graph Rewriting", H.P. Barendregt et al in PARLE: Parallel Architectures and Languages Europe, G. Goos ed, LNCS 259, Springer 1987, pp.159-175].