Invariant-based programming: Difference between revisions

Revision as of 14:40, 22 February 2006

Revision as of 15:20, 22 February 2006

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Writing invariants before program statements has been considered before in a number of different forms by, e.g, M.H. van Emden, [[Edsger Dijkstra|E.W. Dijkstra]], J.C. Reynolds and [[Ralph-Johan Back|R-J Back]].

Most existing programming languages are not ideal for invariants-first programming, since the main organizing structures in algorithmic code are control flow blocks such as <tt>for</tt> loops, <tt>while</tt> loops and <tt>if</tt> statements. This forces the programmer to make decisions about control flow before writing the invariants, which should be avoided. Furthermore, most programming languages do not have good support for writing specifications and implementationsinvariants, since they lack quantifier operators and one can typically not express higher order properties such as permutation of arrays well.

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