kc@rna.UUCP (Kaare Christian) (09/10/85)
In Ford&Wiener's new book on Modula-2 they have an appendix that mentions several new Modula-2 features. Most of these features are the standard things mentioned in Wirth's "Revisions and Amendments to Modula-2" paper of 5/24/84. However Ford&Wiener mention several changes to Modula-2 that aren't in Wirth's paper. Incidentally, these changes also aren't in Wirths "Programming in Modula-2", third edition. Does anyone have any info about these changes? Is the Ford&Wiener list more recent than Wirth's, or have these things been nixed or what? In the following, I am skipping the changes that are common to Wirth's document and Ford and Wiener's appendix, and quoting from Appendix 3 of Ford and Wiener's book on Modula-2; "The unary minus may be used to denote the operation of set complement relative to the base type of the set." "The while and if statements may be defined in additional forms that allow more than one expression and body within a single statement. The syntax of these new forms is still to be specified." "A function procedure may return a value of any structured type, not just a scalar type." "All import lists will begin with the reserved word FROM. Importing an entire module, previously written: IMPORT modulename; is now written FROM modulename IMPORT; This change primarily benefits the implementor rather than the user of Modula-2." The bit about an alternative form of while and if statements is particulary puzzling. Any information on these changes is welcome. Kaare Christian Research Assoc. The Rockefeller Univ. cmcl2!rna!kc