| Plus | |
| Paradigm: | imperative, structured |
| Typing: | static, strong, safe |
| Implementations: | IBM System/370, DEC PDP-11, and Motorola 68000 |
| Year: | 1976 |
| Developer: | Alan Ballard and Paul Whaley at UBC |
| Influenced By: | SUE, Pascal |
| Operating System: | Michigan Terminal System (MTS), OS/VS1 |
Plus is a "Pascal-like" system implementation language from the University of British Columbia (UBC), Canada, based on the SUE[1] system language developed at the University of Toronto, c. 1971.[2]
Plus was developed at the University of British Columbia (UBC) Computing Centre by Alan Ballard and Paul Whaley for use with and for the development of the Michigan Terminal System (MTS), but the code generated by the compiler is not operating system dependent and so is not limited to use with or the development of MTS.
The UBC Plus compiler is written largely in Plus, runs under the Michigan Terminal System (MTS) on IBM S/370 or compatible hardware or under IBM's OS/VS1,[3] and generates code for the IBM S/370, the DEC PDP-11, or the Motorola 68000 architectures.
Plus is based to a large extent on the SUE System Language developed at the University of Toronto, 1971, which in turn had been derived, particularly in its data structure facilities, from Pascal.
Plus is superficially quite different from SUE or Pascal; however the underlying language semantics are really quite similar. Users familiar with the C programming language will also recognize much of its structure and semantics in PLUS.
Goals for the compiler and the Plus language include:[4]
The compiler generates extensive source listings, including cross-references. In addition, it automatically formats the source using strict rules and has a simple mark-up language for comments.
The manual, UBC PLUS: The Plus Programming Language, is available. A description of the source and object libraries available for use with Plus, PLUS Source Library Definitions, is also available.[5]
The "hello, world" example program prints the string "Hello, world!" to a terminal or screen display.
%Title := "Hello world"; %Include(Pluslist); %Subtitle := "Definitions"; %Lower_Case := True; /* Definitions that everyone needs */ %Include(Boolean, Numeric_Types, More_Numeric_Types, String_Types, More_String_Types); /* A tasteful subset of procedure definitions */ %Include(Main); /* Message routine definitions */ %Include(Message_Initialize, Message, Message_Terminate); %Subtitle := "Local Procedure Definitions"; %Eject; definition Main variable Mcb is pointer to Stream_Type; Mcb := Message_Initialize; Message(Mcb, "Hello, world!"); Message_Terminate(Mcb); Mcb := Null; end Main;