Cormac Flanagan. E#ective Static Debugging via Componential Set-Based Analysis. PhD thesis, Rice University, 1997. 346  Home/Search   Document Not in Database   Summary   Related Articles   Check

....an arity error occurs. Both PLT Scheme [16] and Chez Scheme [3] provide case lambda. In both implementations, a caselambda clause parameter list may have a rest parameter, just as for lambda in Scheme [13] 1 In this paper, we describe our extension of the formalism developed by Flanagan [9, 10] for the MrSpidey static de Meunier, Findler, and Steckler were partially supported by National Science Foundation grants CCR 9619756, CDA 9713032, and CCR 9708957, and a State of Texas ATP grant; Wand was supported by National Science Foundation grant CCR 9804115. For Meunier and Steckler, ....

....between covariant and contravariant selectors shows up in the propagation rules covariant prop and contravariant prop. The selector predicate holds when its argument is rng, car, or cdr; the selector predicate holds only for dom. These propagation rules follow the presentation in Flanagan [9], with some simpli cation and notational changes. These rules are repeatedly applied until no new constraints are added. The full details of MrSpidey s constraint solution and type reconstruction algorithms are beyond the scope of this paper, but we attempt here to convey their essence. See ....

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C. Flanagan. Eective Static Debugging via Componential Set-Based Analysis. PhD thesis, Rice University, May 1997.

....all program parts can be executed without raising a type error for at least one tuple of input arguments. The intended use for a complete type checker based on the relation on types induced by CE is a combination with a soft typing system or a system with an output similar to a soft typing system [3, 4] with the following bene ts: The new type checker focuses on a set of provable type errors (i.e. program parts that cannot be executed without raising an error) Obviously, such errors must be corrected. If instead these errors were only indicated as warnings within in a large number of type ....

C. Flanagan. Eective Static Debugging via Componential Set-Based Analysis. PhD thesis, Rice University, Houston, Texas, May 1997.

....output O is quadratic. Note that simpli cation eliminates only extended forms; if further simpli cation could achieve minimization, then the output of this example may be made only linear. However, that would be a di erent analysis problem. In particular, minimization alone takes exponential time [15]. Language features a ecting complexity. Again consider simpli cation after initialization and consider that a is a small constant. In the application, selector forms are constructed only from data construction in programs, and constructor forms are constructed only for selectors and tester; ....

C. Flanagan. Eective Static Debugging via Componential Set-Based Program Analysis. PhD thesis, Department of Computer Science, Rice University, Houston, Texas, May 1997.

....and to start displaying information even when the whole program is not present. Nevertheless, we must acknowledge that DrScheme has nice features that are currently missing in the Bee. The most innovative feature of DrScheme relies on its embedded static debugging analyses (Flanagan et al. 1996; Flanagan, 1997). The key idea is to use a set based analysis (i.e. an abstract interpretation) for static debugging. This usage of abstract interpretation is rather new. The very few systems we know that use abstract interpretation do so for optimization purposes (Rozas, 1992; Serrano Feeley, 1996) These ....

Flanagan, C. (1997). Eective Static Debugging via Componential Set-Based Aanlysis. Ph.D. thesis, Rice University.

....all states which recognize the same language. In the case of subtyping, the rst step is performed by garbage collection, which discards super uous variables and constraints. It is also possible to design an algorithm in charge of performing the second step, as suggested by Flanagan and Felleisen [FF96, FF97, Fla97]. We now present this algorithm, adapted to our system, and name it minimization. It detects equivalent variables, using a method reminiscent of the way equivalent states of a nite automaton are found, and then merges them. We begin with the de nition of the criterion which allows considering ....

....[AWL94] but more complex. Its initial implementation [Aik94] contained unpublished simpli cation algorithms. More recent works by Aiken, F ahndrich et al. AF96, FFSA98, AFFS98, F ah99] describe various simpli cation techniques, many of which share common ideas with ours. Flanagan and Felleisen [FF96, FF97, Fla97] also manipulate set constraints, in order to perform set based analysis. Their system o ers several common aspects with ours; in particular, it provided the inspiration for our minimization algorithm. The main di erence probably lies in the treatment of functions. Indeed, in our system, a ....

Cormac Flanagan. Eective Static Debugging via Componential Set-Based Analysis. PhD thesis, Rice University, May 1997. URL: http://www.cs.rice.edu/CS/PLT/ Publications/thesis-flanagan.ps.gz.

....between theory and implementation. In this rst report, we implement an analyzer for a simple, rst order functional language and show how to use the analysis in a static debugger. 1 Introduction A static debugger assists a programmer in nding potential errors in programs. Flanagan s MrSpidey [3] is a static debugger for the MzScheme programming language, supplied as an extension of the DrScheme programming environment. MrSpidey works in three stages. First, it analyzes the program using an adaptation of set based analysis (SBA) 5, 6] Second, it uses the results of the analysis to ....

....of MzScheme s safety invariants. Finally, it translates the result of the inspection into a program annotation. All provably safe program operations are colored green; all others are colored red. The key to a static debugger is set based analysis. Many authors have described formulations of SBA [1, 3, 6, 7]. Such formulations are e ective for understanding the theory behind SBA, but leave open gaps among that theory, its implementation, and its use for a particular purpose. An implementation needs to confront practical issues not directly addressed by formal descriptions of SBA. While some of the ....

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Cormac Flanagan. Eective Static Debugging via Componential Set-Based Analysis. PhD thesis, Rice University, Houston, Texas, May 1997.

....operators , and , and expr is either 6 C. Flanagan, K.R.M. Leino an integral field declared earlier in the same class or an interesting constant. Interesting constants include the numbers 1, 0, 1, and also constant dimensions used in array allocation expressions (e.g. new int[4]) For each field f of an array type, we also guess a number of inequalities regarding f.length. Although some of these inequalities are more useful than others, we include all of them for completeness. Some of these guessed invariants are mutually inconsistent. For example, if a class declares ....

....as . and the formal parameter is not assigned to by the body ) Second, the suggested annotations are not always correct. The cascading e#ects of incorrect annotations limit the e#ectiveness of the annotation assistant. The second annotation assistant uses a whole program set based analysis [4, 9] to identify which variables and fields are never null and inserts corresponding annotations into the program. These annotations are useful in verifying many dereference operations. However, the inferred annotations do not include numeric Houdini, an Annotation Assistant for ESC Java 15 ....

Cormac Flanagan. E#ective Static Debugging via Componential Set-Based Analysis. PhD thesis, Rice University, Houston, Texas, May 1997.

....or (b) the corresponding correctness proof is beyond MrSpidey s capabilities. MrSpidey s graphical explanation facilities make it mostly straightforward to distinguish these two situations. A complete description of the underlying proof technology used in MrSpidey can be found in related papers [6, 9]. In this paper, we report on our experience using MrSpidey. Section 2 describes the user interface that presents the inferred invariants to the programmer, and section 3 describes our experience using MrSpidey on a variety of programs, including both mature systems and a system under development. ....

Flanagan, C. E#ective Static Debugging via Componential Set-Based Analysis. PhD thesis, Rice University, Houston, Texas, May 1997.

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Cormac Flanagan. E#ective Static Debugging via Componential Set-Based Analysis. PhD thesis, Rice University, 1997. 346

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