Accession Number : ADA113743

Title :   Implementation of Parnas' it-ti Construct in LISP.

Descriptive Note : Technical rept.,


Personal Author(s) : Samples,A Dain

PDF Url : ADA113743

Report Date : Mar 1982

Pagination or Media Count : 22

Abstract : D.L. Parnas has recently proposed (1) a new programming control structure the it-ti. This construct is a synthesis of several ideas in programming theory including iteration, conditionals, and Dijkstra's guards (2) It has been implemented in a LISP interpreter (8) as a more structured replacement for the traditional prog construct. Several programming examples are given that compare the use of the it-ti with the more conventional programming constructs. These examples will also show that the it-ti fails to satisfy several criteria for programming constructs including manageability and visibility. An appendix to this report contains an extension of Dijkstra's concept of the 'weakest precondition' to the it-ti. (Author)

Descriptors :   *Programming languages, Iterations, Comparison, Synthesis, Visibility, Simplification, Computer programming, Control systems

Subject Categories : Computer Programming and Software

Distribution Statement : APPROVED FOR PUBLIC RELEASE