LFC is a functional language based on recursive functions defined in context-free languages. In this paper, a new pattern matching algorithm for LFC is presented, which can represent a sequence of patterns as an integer by an encoding method. It is a rather simple method and produces efficient case-expressions for pattern matching definitions of LFC. The algorithm can also be used for other functional languages, but for nested patterns it may become complicated and further studies are needed.
It is intended to establish the recursive function theory on context free languages (CFLs). In this paper, the function class CFRF and its proper subclass CFPRF were defined on CFLs; it is quite straightforward to use them for describing non-numerical algorithms. In fact, they are respectively the partial recursive functions and primitive recursive functions of context free languages. The structure induction method for proving CFPRF function properties was presented. A method for CFL sentence enumeration was given, the minimization operator was defined. Based on CFL sentence enumeration, the minimization operator evaluation method was given. Finally, the design and implementation principles of executable specification languages with the CFRF as theoretical basis were discussed.
In this paper we proved that the function class CFRF and its proper subclass CFPRF are respectively the partial recursive functions and primitive recursive functions of context free languages (CFLs). Also we discussed the relation between them and recursive functions defined on other domains . It is indicated that the functions of natural numbers and/or symbol strings (words) are functions of CFLs. Several frequently used primitive recursive functions on words were given, including logical connectives, conditional expressions. Also the powerful operators (bounded maximization and minimization operators) for constructing primitive recursive functions were defined. Two important nontrivial algorithms, the characteristic function of arbitrary CFL and the parse function of CFL sentences were constructed. Based on them, the method for extending or restricting function domain was described.
