ion of LOTOS Abstract Data Types Hubert GARAVEL∗ Laboratoire de G´enie Informatique Institut I.M.A.G. GRENOBLE FRANCE This article describes an experiment with the compilation of the data part of Lotos. Using a pattern-matching compiling algorithm described in [Sch88], a tool named Cæsar.adt was d. It enables Lotos abstract types to be translated automatically into corresponding concrete types, implemented in the C language. This paper intends to give a fair idea of the usefulness of this algorithm, when it is combined with appropriate data representations. On several case studies taken from OSI descriptions, this paper explains the basic principles of the translation and shows the great quality of the generated code, which is likely to have better performances than other existing approaches.