xerox 19770926 Mesa 3.0 Tasks free download

File name 19770926_Mesa_3.0_Tasks.pdf

XEROX INFORMATION PRODUCTS GROUP System Development Division September 26, 1977 IIr.OX SDD ARCHIVES To: File I have read and un(,en;t"od From: Subject: John Wick Mesa 3.0 Tasks Paees Revi~wer ----- '1'0 ____ b& "c:_ ~ .-.._-,.. _ Keywords: Mesa, Work Plan # of P",S_ _ R".t. 11~DD.331 Filed On: MESADONE30.BRAVO This memo identifies those items from the Mesa task list that have been implemented in Mesa 3.0. An update of the task list which reflects these changes will be forthcomming shortly. Items are organized alphabetically by major component References are enclosed in square brackets. To distinguish among mUltiple works by the same person, a terse abbreviation for the title of the reference has been appended to the author's name (e.g., [LampsonCD*]). Some items (marked with #) have been retained temporarily in Mesa 3.0 to ease conversion; these will be removed in the first maintenance release. Language Boolean Enumerated Type Defining the built-in type BOOLEAN as an enumerated type would altow it to be used as a variant record tag. This case occurs frequently in Diamond data structures. [WickLWG] Data Modules (#) The destinction between DATA and PROGRAM modules is no longer meaningful, since all modules are started only once under the new scheme proposed for the binder. Data modules will ~e retained temporarily for compa/ability. [Sweet] Directory Names In, conjunction with other changes which improve type checking (primarily export checking for the new binder), the compiler will now verify that the name in the DIRECTORY statement matches the one in the corresponding definitions or program module. The binder will also make this check. [MesaLM] Empty Intervals Allowing empty intervals (especially for array index sets) in type definitions would provide some help in implementing sequences until they are incorporated into the language. Mesa 3.0 Tasks 2 External Dec/arations (#) The new binding scheme requires that all references to types defined outside a module must be obtained from included modules. The EXTERNAL attribute will therefore be removed from the language. It will be retained temporarily for compatability. [Binder, Sweet] Implementing/ Sharing (#) The IMPLEMENTING construct will be replaced by EXPORTS. For compatability with IM