Zork: a type-checker for Z from York

Z specifications have been written at York for some years. However, the tool support was minimal: some troff macros to draw schema boxes, and fancy characters that were formed by overlaying existing characters. The aim of the authors' work was to rectify this situation, without requiring major changes to the existing specifications. They started by improving the typesetting tools by drawing a Z font and improving their troff previewer for the Sun workstations. The authors provided a core for Z by deriving an unambiguous LALR(1) grammar and applying yacc to this grammar to obtain a parser for Zork. They present a small example specification to demonstrate Zork's capabilities. It especially shows the kind of errors that a type-checker can detect and illustrates how interactive browsing aids the reporting and correction of these errors.<
>