MERILL: An equational reasoning system in standard ML

Abstract

MERILL is a general purpose order-sorted equational reasoning system. Written in Standard ML, it has been developed by the author at the S.E.R.C. Rutherford Appleton Laboratory (RAL) and the Dept of Computing Science at Glasgow University. The development of MERILL was inspired and influenced by the ERIL (Equational Reasoning: an Interactive Laboratory) system developed by Jeremy Dick at RAL and Imperial College, London. This system used order-sorted reasoning in a practical equational reasoning system. However, ERIL was slow, and lacked significant features. MERILL is a entirely new implementation which retains the major features of ERIL whilst being significantly faster and having new facilities. An important extension is the integration of order-sorted reasoning with associated-commutative (AC) operations. The system incorporates more recent work on this, for example. Thus it is comparable with ELIOS-OBJ rather than more traditional rewriting systems. Standard ML was chosen due to its ease of use and of modifiability through its module system, together with the emergence of efficient implementations.

On leave from SERC, Rutherford Appleton Laboratory, Didcot, OXON, OX11 0QX, U.K.