Sorted collection and map types for OCL

The OCL collection types defined in the OMG v2.4 standard are a key part of the language, and corresponding types can now be found in most modern programming languages such as Java, C# and Python. Further aggregate types, particularly maps, have been added in revised OCL versions. In this paper we give a rationale for extending the OCL collection and map type system with intrinsically-sorted versions of these aggregate types. We show that these types have strong semantic properties and that their use can improve the efficiency of generated code.