Gregory F. Johnson and Janet A. Walz. A maximum ow approach to anomaly isolation in uni cation-based incremental type inference. In Conference Record of the Thirteenth Annual ACM Symposium on Principles of Programming Languages, pages 44-57. ACM Press, January 1986.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....to a type error. We classify systems using this approach as explanation systems, e.g. 4, 15, 55] Another approach is to provide a better error report, without necessarily explaining the inference that lead to the error. We classify systems using this approach as error reporting systems, e.g. [5, 14, 26, 32, 59]. A third approach is to provide a mechanism for the programmer to probe the type of subexpressions [5] To compare those approaches, a manifesto for good type error reporting is proposed. The manifesto is introduced in the next section. 2.3 A Manifesto for Good Type Error Reporting In [69] we ....

....5, prior to discussion of our human like explanation system. 2.5 Error Reporting Systems Error reporting systems can improve over the W and M algorithms by making explanations comprehensive and more intuitive. There have been several approaches, including Wand s system [59] Johnson and Walz [26], Turner [58] Bernstein and Stark [5] McAdam [32] Dinesh and Tip [14] Choppella [13] and Gomard [17] 2.5.1 Error Reporting Systems 2.5.2 Wand s system Wand s system [59] is the rst system that records the sites that contribute to each type deduction when type errors are detected, and uses ....

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Gregory F. Johnson and Janet A. Walz. A maximum ow approach to anomaly isolation in uni cation-based incremental type inference. In Conference Record of the Thirteenth Annual ACM Symposium on Principles of Programming Languages, pages 44-57. ACM Press, January 1986.

....whole list is shown which may be quite long. Finding the candidate which has the wrong type might be dicult due to the amount of information given. Perhaps it is sensible to automatically calculate a biggest subset of the list that has no con icts. This is similar to the idea of Johnson and Walz [JW86] where a majority decision is taken. Up to now we have no experiences how useful the set of type information is to nd an error. In case it turns out that our approach speeds up the nding of type errors, full Haskell 98 support would be valuable. Currently our language is a simple functional ....

....collect all type information for each identi er and unify these at the point where the variable is de ned [BS95, Jun99] This is close to how our tool works. In the event of an error, this technique allows to search for a biggest uni able subset and report all other occurrences as errors [JW86] This improved algorithm may be implemented in a future version of Hugs [JR, Nor] Besides generating better diagnostic messages, a couple of interactive tools have been developed to explain how type inference works and how the compiler derives the type error [BS94, Soo90, DB94] Most of these ....

G.F. Johnson and J.A. Walz. A maximum- ow approach to anomaly isolation in unication-based incremental type-inference. In Proc. 13th ACM Symposium on Principles of Programming Languages (POPL '86), pages 44-57, 1986.

....deductions about the type of a variable. A similar approach is discussed by Beaven and Stansifer [3] where an interactive system traces all deductive steps to construct an explanation for a type con ict. Various techniques to improve type error messages use constraints on types. Walz and Johnson [12] collect a set of type equations that can be inconsistent. To resolve contradictions, variables are predominantly assigned a type, such that most of the hypotheses are satis ed. Unfortunately, the order in which the equations are solved determines which con ict is reported. Aiken et al. 2] show ....

J. A. Walz and G. F. Johnson. A maximum ow approach to anomaly isolation in unication-based incremental type inference. In Conference Record of the 13th Annual ACM Symposium on Principles of Programming Languages, pages 44-57, St. Petersburg, FL, January 1986.

....The systems that use this approach are classi ed as error explanation systems, e.g. 1, 4, 11] Another approach is to provide a better error report, without necessarily explaining the inference that lead to the error. Systems using this approach are classi ed as error reporting systems, e.g. [13, 5, 2, 8, 3]. A third approach is to provide a mechanism for the programmer to probe the type of subexpressions [2] 4.1 Error Explanation Systems There have been several error explanation systems. For example, the system of Duggan and Bend uses a modi ed uni cation algorithm to record the reasons which led ....

....system lists the possible error sites; some of them are not the direct source of the type inconsistency. It is not clear if there is any relationship between the candidate error sites: the user needs to check the types of the proposed error sites against their own intentions. Johnson and Walz [5] give a maximum ow approach to decide which usage is the most likely error source. The usage that is in the minority is a candidate for the mistake. However for many errors there is one correct usage and one incorrect usage and it is not clear how often the minority can be isolated, and sometimes ....

Gregory F. Johnson and Janet A. Walz. A maximum ow approach to anomaly isolation in unicationbased incremental type inference. In Conference Record of the Thirteenth Annual ACM Symposium on Principles of Programming Languages, pages 44-57. ACM Press, January 1986.

....sites; some of them are not the direct source of the type inconsistency. It is not clear if there is any relationship between the candidate error sites: the user needs to check the types of the proposed error sites against their own intentions. Maximum ow approach: Greg F. Johnson and Janet Walz [2] give a maximum ow approach to decide which usage is the most likely error source. The usage that is in the minority is a candidate for the mistake. But for many errors there is one correct usage and one incorrect usage and it is not clear how often the minority can be isolated, and sometimes the ....

Greg F. Johnson and Janet Walz. A maximum- ow approach to anomaly isolation in unication-based incremental type inference. In Thirteenth Annual ACM Symposium on Principles of Programming Languages, pages 44-57. Association for Computing Machinery, ACM Press, January 1986.

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