Subject: Re: Prolog vs. Lisp From: Erik Naggum <firstname.lastname@example.org> Date: 1997/04/02 Newsgroups: comp.ai,comp.lang.prolog,comp.lang.lisp Message-ID: <email@example.com> * Susan Fisher RSTC Contractor | I have a similar question. I am taking an AI course where we may program | in any language we choose. I debating the use of C, C++, and LISP. I am | looking for any insight on the pros and cons of these languages. I am a | very new programmer and have honestly never had the option of which | language to use! And advice would be greatly appreciated. rest assured that someone will come along and proclaim Lisp dead or that they can't use it. this is really only a reflection of their own attitude, _possibly_ only envy for those who can still use it for fun and profit, and has nothing to do with the language. you will find similar "reasons" not to use any other language, too. Common Lisp was approved as ANSI Standard on 1994-12-08. the vendors in the Lisp market are growing. C is very close the actual processor, which means you get to do everything yourself. while the model of the processor that C employs is long gone, the simplicity of the model still makes is possible to be fairly certain of how the machine will respond to your instructions. this gives programmers a feeling of "control" that is very intoxicating. it is also easy to confuse this "control" with "efficiency", but computers are not efficient in intuitive ways, in fact haven't been for years. C is used to implement operating systems and fundamental parts of many other languages, and is an invaluable language to know in today's market. C was approved as ANSI standard on 1989-12-14. it is possible to learn C well in about 2 months, and it is simple enough to become an expert in about a year. (I have programmed in C for 15 years.) C++ tries very hard to be an object-oriented language, but doesn't quite make it. C++ is an extremely complex language, as evidenced by the draft ISO standard. the syntax is so complex that common tools to parse and process programming languages fail to handle C++. the precise meaning of several of its constructs is still open to debate, and several vendors who have produced large C++ systems still disagree profoundly on what they mean. C++ leaves a lot to the implementation for the same reason C does, but that reason was valid for C. the previous draft standard was rejected by the international programming language community, as being grossly inadequate for an international standard. it is unlikely that C++ will reach standard status for several years, still. even if it does become a standard, the vendors in the C++ market are not known for their willingness to follow standards in the first place, and some even make a point of doing weird things that lock you into their environment. the creator of C++, quote a Bell Labs proverd that "language design is library design", so you improve the C++ system to meet your needs by adding new objects and new functions for them, but you cannot expand on existing objects. it is possible to learn C++ well in about 18 months, but it takes several years to become, and constant vigilance to remain, an expert, since the language is still in flux. (I programmed in C++ for about a year (less than it took to learn it well, which is why I quit -- life is too long to know C++ well), but still help others understand C++ concepts by relating to other languages (typically C and Lisp) where the concepts are much better expressed.) Common Lisp is object-oriented all the way. the data types in Common Lisp form a hierarchy, instead of being all distinct. objects are typed, but variables are not. (in C/C++, all objects are just so many bits, their meaning depending on how you view them. this is "the hardware way".) this type hierarchy means that polymorphism and all that fine stuff works for built-in types. object-orientation in Common Lisp is based in generic functions that take arguments of any type, and for which methods are specialized on the types of any number of the arguments. Common Lisp has a large number of built-in types and operators, but you don't need to know them all. the difference between a new and an experienced Common Lisp programmer is not as much in how much of the built-in facilities they use, but in how the experience programmer builds the language "upwards" to his problem so it is easier to express himself. this was the real intention behind object-oriented languages (as expressed in the early papers on Simula, the first object-oriented programming language), but as long as only objects and functions can be built by the programmer, not language constructs, it doesn't really work all that well. Common Lisp is one of very few languages that allow the programmer to define application-oriented languages. it is possible to learn Common Lisp well in about a month, but to master it takes many years and is a constant source of enjoyment to learn even more elegant ways to do things. (I first met Lisp in 1978 or so, always returning to its concepts while programming in other languages. I have programmed in Common Lisp for real for nearly four years, now. I couldn't earlier, mostly because Common Lisp environments were too demanding of the hardware I could use, but this has changed, today, it's C++ and the like that are too demanding for commonly deployed hardware.) I envy you the opportunity to study Lisp and C and C++ with fresh eyes. #\Erik -- I'm no longer young enough to know everything.