Abstract :
One of the most important problems in computer development today is the difficult job of constructing programs and programming languages to handle a wide variety of tasks. There are two pure approaches to programming language design and an endless number of mixed approaches lying between them. One of the pure approaches, often taken by graduate students in universities, is to create a new programming language for each problem. The other approach, perhaps typified by certain supporters of PL/I, is to design a language which is intended hopefully to be all things to all programmers. Unfortunately, neither of these pure approaches is really practical. People have long recognized the common features of programming problems and most agree that certain techniques are applicable to almost all of them. However, with the burgeoning use of the machine it is not possible to assert with any degree of confidence that we have discovered all useful techniques. A reasonable way to proceed seems to be to design a programming language which contains most of the common features which people have discovered in various problems, but which allows the user to extend and mold the language to suit his particular application.
