Functional programming is well suited for equational reasoning on programs. In this paper, we are trying to use this capability for program comprehension purposes. Specifically, in a program understanding process, higher-order operators can work like abstract schemes in which we can fit formal specifications calculated from the source code. Such specifications are calculated by a transformational process which we call reverse program calculation that operates on both notations: pointwise and pointfree. Once a specification matches an abstract schema, a new refactoring phase leading to a clearer source code takes place. At the same time, an unambiguous behavioural understanding is reached because we give a mathematical description of the abstract schemes. To provide a more complete and realistic perspective of the approach, we use recursive operators that can handle side effects.

Abstract — In this paper a new maintenance scenario is outlined based on refactoring techniques. Specifically, refactoring techniques are classified according to two opposed program properties: understanding and efficiency. Understanding oriented refactoring disassembles the program preparing it for maintenance, whereas those oriented to efficiency rearrange it for running. Also, we show the challenges raised from this new perspective on maintenance. At present, this ongoing research is being carried out in the functional setting.