ALGOL W

ALGOL W
ParadigmsMulti-paradigm: procedural, imperative, structured
FamilyALGOL
Designed byNiklaus Wirth, Tony Hoare
First appeared1966; 58 years ago (1966)
Typing disciplineStatic, strong
ScopeLexical
Implementation languagePL360
PlatformIBM System/360
OSOS/360, MTS
Influenced by
ALGOL 60
Influenced
Pascal, Modula-2

ALGOL W is a programming language. It is based on a proposal for ALGOL X by Niklaus Wirth and Tony Hoare as a successor to ALGOL 60. ALGOL W is a relatively simple upgrade of the original ALGOL 60, adding string, bitstring, complex number and reference to record data types and call-by-result passing of parameters, introducing the while statement, replacing switch with the case statement, and generally tightening up the language.

Wirth's entry was considered too little of an advance over ALGOL 60, and the more complex entry from Adriaan van Wijngaarden that would later become ALGOL 68 was selected in a highly contentious meeting. Wirth later published his version as A contribution to the development of ALGOL.[1] With a number of small additions, this eventually became ALGOL W.

Wirth supervised a high quality implementation for the IBM System/360 at Stanford University that was widely distributed.[2][3] The implementation was written in PL360, an ALGOL-like assembly language designed by Wirth. The implementation includes influential debugging and profiling abilities.

ALGOL W served as the basis for the Pascal language, and the syntax of ALGOL W will be immediately familiar to anyone with Pascal experience. The key differences are improvements to record handling in Pascal, and, oddly, the loss of ALGOL W's ability to define the length of an array at runtime, which is one of Pascal's most-complained-about features.

  1. ^ Wirth, Niklaus; Hoare, C. A. R. (June 1966). "A contribution to the development of ALGOL". Communications of the ACM. 9 (6): 413–432. doi:10.1145/365696.365702. S2CID 11901135. Retrieved 7 October 2020 – via Association for Computing Machinery.
  2. ^ Bauer, Henry R.; Becker, Sheldon I.; Graham, Susan L.; Forsythe, George E.; Satterthwaite, Edwin H. (March 1968). Technical Report Number: CS-TR-68-89. Computer Science Department (Report). Stanford University. (Various documents for Stanford's 1972 implementation of ALGOL W; this report includes the ALGOL W Language Description.
  3. ^ Sites, Richard. "ALGOL W Reference Manual" (PDF). i.stanford.edu. Stanford University. Retrieved 24 July 2022.