User-friendly syntax: design and presentation

Abstract

A user-friendly programming system should have a user-friendly syntax; natural and systematic, easy to understand and use. Syntax should allow substitution of semantically similar constructs by each other. Syntax should also be flexible and allow several variants of syntactic notations to reduce the burden of memorizing rigid syntactic notations and to make it possible for a user to think more about ‘what’ instead of ‘how’. Nowadays programming languages, e.g. Ada, do not obey these principles. Their complexity is mainly caused by their nonsystematic and rigid syntax. This together with unformal and ambiguous presentation of syntax makes Ada difficult to use and Ada parsers inefficient. Uniform, natural and flexible syntax, where several variants of syntactic notations and abbreviations are allowed and minor syntactic errors automatically corrected, can be introduced by systematic top-down design using multi-level grammars. Systematic design and presentation allows greatly improved syntax without increasing size of the syntax grammar and the complexity of the parser.