Procedure definition and higher-order programming in Hyperlogo

The power of Logo derives from the fact that, like Lisp, it is a functional programming language. But, unlike Lisp, Logo permits special syntactic features to make programs easier to read and write. From the point of view of the Logo interpreter these special features require separate treatment, which has tended to result in rather cumbersome implementations. However, the concepts of the procedure object and syntactic sugar can be used to greatly simplify the design of the interpreter. In this paper, it is shown how a procedure can be defined using a procedure object and how syntactic sugar forms a bridge between conventional Logo syntax and the new procedure definition. A mechanism for higher-order programming is also described, which provides a powerful means for the expression of algorithms.