- Prolog programming language family
- Functional logic programming languages
First we shall discuss some languages falling under the first category:
1. Algebraic logic functional programming language or ALF: Combines the techniques of both the logic programming techniques and the functional programming techniques. This language is based on the horn clause logic. The resolution rules for solving the literals and evaluating the functions form the foundation for the operational semantics of this language. It follows a left – most inner – most narrowing strategy for reducing the number of steps in solving a problem. Thus, these operational semantics are much more efficient and powerful than those produced by the resolution strategy of prolog.
2. Alice ML: This programming language was designed at the Saarland University and is actually a standard ML dialect. But it has the support for concurrency (this includes distributed computing as well as multithreading), lazy evaluation, constraint programming etc. this language uses a relation concept called “promise” according to which a future value provided by one thread will be computed to another thread. Thus data flow synchronization is possible in Alice ML by use of future typed variables and promise concept.
5. Leda: It stands for ‘library of efficient data types and algorithms’ and is a multi – paradigm – programming language. The language is used for mixing the features of logic based, object based, functional and imperative programming in to one.
9. Oz: This one is another multi – paradigm programming language for the purpose of programming language education. It was developed in the year of 1991 at the Swedish institute of computer science. A primary example of Oz implementation is the Mozart Programming system. The system comes with an open source language and supports many platforms including Microsoft windows, mac os x, Linux, Unix etc.
10. Visual prolog
Now we shall see the second category of languages i.e., the functional logic programming languages:
1. B – prolog: This is the high – level implementation of the prolog and has some additional features such as the event handling rules, matching clauses, arrays, declarative loops, tabling, constraint solving etc. it was developed in 1994 and now is a popular CLP system. Though B – prolog is a commercial product, it comes free for research purposes. A clause in which the input/ output unifications and the determinacy are denoted in an explicit way is called a matching clause.
The matching clauses are translated in to the respective trees by the compiler and indexes are generated. This compilation is easier when compared to the compilation of the normal clauses in prolog. B – prolog overcomes the absence of active sub goals programming facility in prolog by introducing the action rules or AR which is a powerful but simple language for serving this purpose. The sub –goals are called agents. Activation of an agent is followed by the execution of an action. The CHIP system heavily affected the finite domain solver of B – prolog. For creating arrays, a built – in is provided by B – prolog called new_array(X, Dims) where x stands for uninitialized variable and Dims for positive integers for specifying the array dimensions.
3. GNU prolog
5. KL0 and KL1
7. Objlog: This one is a frame based language that combines two things: Prolog II and object from CNRS.
10. Strawberry prolog
12. Visual prolog