Relationship between PL and Correctness ( 3) Understandability The primary goal of a programming language is accurate communication among humans Readability more important than writeability Well"punctuated"(easy to directly determine statement types and major subunits without intermediate inferences) Use of distinct structural words(keywords, reserved words for distinct concepts(no overloading, e. g, for equal, assignment) Avoidance of multiple use of symbols unless serve completely analogous functions(e.g, commas as separators, parentheses for grouping) Necessary to be able to see what is being accomplished at a higher level of abstraction Permit programmers to state their "intentions"along with instructions necessary to carry them outCopyright Nancy Leveson, Sept. 1999 Relationship between PL and Correctness (3) Understandability "The primary goal of a programming language is accurate communication among humans." Readability more important than writeability. Well "punctuated" (easy to directly determine statement types and major subunits without intermediate inferences) Use of distinct structural words (keywords, reserved words) for distinct concepts (no overloading, e.g., = for equal, assignment) Avoidance of multiple use of symbols unless serve completely analogous functions (e.g., commas as separators, parentheses for grouping). Necessary to be able to see what is being accomplished at a higher level of abstraction. Permit programmers to state their "intentions" along with instructions necessary to carry them out. � c