FLEXIPL.INFO

Natural languages such as English or German possess a fixed grammar or syntax, but an extensible vocabulary: One can always introduce new words or compound terms, define their meaning in terms of other, already known concepts, and use them afterwards. Very similar, programming languages have a fixed grammar or syntax - and if you violate it, the compiler will refuse to understand you - and an extensible vocabulary: One can freely introduce new types, variables, and functions, define their meaning, and use them afterwards. So, having an extensible vocabulary is crucial for a programming language, but to have an extensible syntax would also be useful... This can be demonstrated by a comparison with mathematical notation: Even though functions play a fundamental role in mathematics, mathematicians do not use function syntax for each and every thing. Instead, they have developed lots of different syntactic forms that can be used to express things more nicely. For example, they write..