ERWIN: Reduction-System Window-Oriented Editor. User's Guide

摘要

ERWIN is the editor of the OREL-Reduction system. It offers a convenientdevelopment and programming environment for the construction and maintenance of reduction expressions of OREL/2, as well as command procedures written in OREL/C. ERWIN is syntax-oriented: Insertion and modification of subexpressions refers always to complete syntactical units as defined by the corresponding grammar. Since only syntactically correct expressions may be entered, the syntactic correctness of the whole program is guaranteed by construction. ERWIN is cursor-driven: The subexpression to be edited or changed by a command is selected with the cursor. ERWIN is window-based: There are several language specific window-types. For every window type a number of windows can be opened, limited by a system variable. Expressions of the language corresponding to the entire window-type can be edited in any window. Windows can be arranged side by side, overlapping, or completely covered. The currently active window is always shown entirely.