The Script Programming Language

The Script Programming Language

Author: Jeff Stephenson
Date: 4 April 1988

Introduction

The Script adventure game language is an object-oriented language with a Lisp-like syntax. It is compiled by the sc compiler into the pseudo-code which is used by the interpreter, sci.

We will begin our discussion of the language with its basic Lisp-like characteristics, then go on to the object-oriented parts of the language.

As is Lisp, Script is based on parenthesized expressions which return values. An expression is of the form

Code:

      (procedure [parameter parameter ...]).

The parameters to a procedure may themselves be expressions to be evaluated, and may be nested until you lose track of the parentheses.

Unlike Lisp, the procedure itself may NOT be the result of an evaluation. An example of an expression is

Code:

      (+ (- y 2) (/ x 3))

which would be written in infix notation as

Code:

      (y - 2) + (x / 3).

All expressions are guaranteed to be evaluated from left to right. Thus,

Code:

      (= x 4)
      (= y (/ (+= x 4) (/= x 2)))

will result in y = 2 and x = 4.

Comments in Script begin with a semi-colon, ';', and continue to the end of the line.