Currently the operators and basic predicates of the Event-B mathematical language supported by Rodin are fixed. We propose to extend Rodin to support user-defined data types and associated operators including including inductive data types. Users will be able to define operators of polymorphic type as well as parameterised predicate definitions.
Details of the proposal may be found in this report : 
The proposal consists of considering three kinds of extension:
- Extensions of set-theoretic expressions or predicates: example extensions of this kind consist of adding the transitive closure of relations or various ordered relations.
- Extensions of the library of theorems for predicates and operators.
- Extensions of the Set Theory itself through the definition of algebraic types such as lists or ordered trees using new set constructors.