Generative text using classical nondeterminism

Many recent generative text systems combine a context-free grammar base with some set of extensions such as tagging or inline JavaScript. We argue that the restriction to CFGs is unnecessary and that the standard pattern-directed, nondeterministic control structures common to Prolog, definite-clause grammars, and many HTNs, support a superset of these capabilities while still being simple to implement. We describe Step, a generative text system for Unity games based on higher-order HTNs that so far as we can determine from published descriptions, generalizes this previous work. We then describe syntactic extensions to make Step more natural as a text-authoring language. Finally, we discuss how Step and similar systems can be implemented very compactly in modern mainstream programming languages.