An Implementation of the Task Algebra, a Formal Specification for the Task Model in the Discovery Method

This paper describes an implementation of the Task Algebra, a formal model of hierarchical tasks and workflows, in the Haskell programming language. Previously we presented the Task Algebra as a formal, unambiguous notation capturing the kinds of activity and workflow typically seen in business analysis diagrams, similar to UML use case and activity diagrams. Here, we show how the abstract syntax for the Task Algebra may be parsed and then semantically analysed, by a suite of Haskell functions, to compute the execution traces of a system. The approach is illustrated with a case study of a journal management system. The results show how it is possible to automate the semantic analysis of requirements diagrams, as a precursor to developing a logical design.