FUNC : A Functional Language : : : and more ! Markus

FUNC is a functional language with the ability to incorporate C++ components. Unlikèmostly-functional' languages, like Scheme or SML, FUNC does not provide an assignment statement or statement sequences. Our approach to the integration of the functional and imperative paradigms is the concept of mixed-language programming on a module level. 1 Introduction Although the practical advantages of functional languages are widely approved in the academic community Hug90, Llo94], the acceptance in software industry is small. A major obstacle for the introduction of functional languages like Haskell or Miranda is that no possibility is provided to reuse existing (imperative) programs. Therefore, functional languages can only be used for the development of new software, whereas maintenance or extension of existing systems can not be done functionally. FUNC is a functional language with the ability to incorporate C++ components. Functions and algebraic data types deened in modules programmed in FUNC can use and can be used directly by procedures and classes in C++ modules. There is no need for special inter-language interfaces in order to exchange data between the two worlds. Data structures which were generated using constructors can be used by imperative procedures, including suspended computations due to lazy evaluation. Even higher-order functions like map or filter can be incorporated by imperative components. We implement our language by compiling FUNC programs to C++. Each functional type and each function is mapped to an equivalent imperative class, or imperative procedure, respectively. Hence, in contrast to implementations of functional languages based on abstract machines FH88, PL92, Pey93], we do not need an additional run-time environment for maintaining tasks like data structure representation , higher-order features, and simulation of lazy evaluation. The major advantage of this approach is the possibility to use the same data structures for the functional and