Refal

Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online.Refal is a pattern matching programming language. The name Refal stands for Recursive functions algorithmic language. As defined by, "Refal (for REcursive Functions Algorithmic Language) is a functional programming language oriented toward symbol manipulation: string processing, translation, artificial intelligence". It is one of the oldest members of this family, first conceived in 1966 as a theoretical tool with the first implementation appearing in 1968. Refal combines mathematical simplicity with practicality for writing large and sophisticated programs.Unlike Lisp, Refal is based on pattern matching. Due to that, a typical program in Refal is on average two or three times shorter and more readable than a Lisp analog. Compared to Prolog, Refal is conceptually simpler. Its pattern matching works in the forward direction rather than backwards (starting from the goal) as in Prolog. This is a more natural approach to writing algorithms which also makes them easier to test and debug.