Karen L. Bernstein and Eugene W. Stark. Debugging type errors (full version). Technical report, State University of New York at Stony Brook, Computer Science Department, November 1995. http://www.cs.sunysb.edu/stark/REPORTS/INDEX.html.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....in particular for object oriented languages [28] and for ML [27] Providing accurate positional information for type inference errors in ML is a difficult problem. Several proposals that rely on adapting or extending the underlying type system or inference algorithm have been presented (see, e.g. [5, 36]) In contrast, applying dependence tracking to a rewriting based implementation of an ML type inferencer might require no changes to the type inference algorithm. Although a slice can be computed for each reported type inference error, it is unclear how accurate such slices will be in practice. ....

Bernstein, K. L., and Stark, E. W. Debugging type errors (full version). Tech. rep., State University of New York at Stony Brook, Computer Science Department, 1995.

....is against the philosophy of this project as expressions should be regarded as they stand alone before their relationships are studied, so that undetected mistakes in the context do not cause the appearance of internal errors in the subexpression. Another notable paper is by Bernstein and Stark [BS95] which introduces typings for open expressions. The paper is significant in two ways: it defines the inference in an alternative set of operational semantics, and the inference is of open expressions without an environment. The general technique of the paper is to first define an operational ....

....given. 5 Progress so far Work so far on this project has concentrated on inference rather than analysis and debugging. Initially time was spent investigating the state of the art: the classical results by Milner and Damas ( DM82] Mil78] Dam85] more novel forms of type inference ( LY98] [BS95]) and work related to mine (in explanation ( DB96] BS93] debugging ( Rit93] and programming environments ( RT97] WBL97] In addition to studying related material, I have produced two technical reports and am working on a third paper which I hope to submit to a conference. 5.1 Symmetric ....

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Karen L. Bernstein and Eugene W. Stark. Debugging type errors (full version). Technical report, State University of New York at Stony Brook, Computer Science Department, November 1995.

....type inference. The reported location of the error may be far away from the code that causes the error, and the error message itself may confuse those who don t understand the underlying unification algorithm. Elaborate methods have been proposed to help users understand errors in type inference [21, 22, 23]. This particular collection of combinators arose as part of an effort to improve the error reporting ability of a compiler designed to halt after a single error. The ERROR and OK combinators provided the basic ability of adjoining an error value to any type. The next additions were emap, which ....

Karen L. Bernstein and Eugene W. Stark. Debugging type errors. Technical report, State University of New York at Stony Brook, Computer Science Department, October 1995.

....be misleading [Wan86] This problem has motivated a number of authors to present means for producing more useful information about untypeable programs. The authors who have presented means for helping programmers have all selected a different form of information. For example Bernstein and Stark [BS95] chose to describe the types of unbound identifiers, while Mitchell Wand [Wan86] describes locations in the program which may contain a mistake and Duggan [Dug98] produces type explanations. This paper presents a way of capturing information about the types of parts of a (possibly untypeable) ....

....is that these analyses only use the graph: they do not create any other structures such as substitutions and do not traverse the syntax tree, thus it can be said that the graph encodes all the information obtained. 4 Bernstein And Stark Assumption Environments Bernstein and Stark s system [BS95] is concerned with the types which unbound identifiers must have in order for a program to be well typed. The results of their inference algorithm can also be obtained by reading graphs. 4.1 Summary of Bernstein and Stark s Technique Bernstein and Stark present their debugging system as a set ....

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Karen L. Bernstein and Eugene W. Stark. Debugging type errors (full version). Technical report, State University of New York at Stony Brook, Computer Science Department, November 1995. http://www.cs.sunysb.edu/~stark/REPORTS/INDEX.html.

....substitutions were made during unification. Their interest is in producing meaningful messages after some unification fails, whereas this paper is interested in making unification fail at the appropriate point. Beaven and Stansifer [BS93] provided another explanation facility. Bernstein and Stark [BS95] provide a novel type inference algorithm based on the unification of type environments. Like the algorithm in this paper, their s is symmetric and has no left to right bias. Lee and Yi [LY98] discuss a folklore algorithm. They prove that it can reject programs sooner than the classic algorithm. ....

Karen L. Bernstein and Eugene W. Stark. Debugging type errors (full version). Technical report, State University of New York at Stony Brook, Computer Science Department, November 1995. http://www.cs.sunysb.edu/~stark/REPORTS/INDEX.html.

....valid program using steps guaranteed to preserve syntactic validity. Hence, Whittle s work is not of such direct relevance to this work. Karen Bernstein and Eugene Stark presented a modified version of algorithm W which allows the type checking of open expressions with unbound variables [BS95] Their idea is that programmers wanting to find out about their program can find out what types an expression required its environment to have. This has not yet been implemented in any widely available system. Yang Jun s interest is the visualisation of types as graphical symbols, the psychology ....

....a conflict Even though vertices have multiple edges, there are no branches for a program with unbound identifiers. The unbound identifiers are marked with the type constructor. In Section 5.4. 1 we will see how to read the required types of unbound identifiers following the example of [BS95] The final way in which a graph can indicate that its program is untypeable is if it contains a cycle, as in Figure 5.8. This corresponds to an occurs error in traditional type inference. Cycles are indirect, as they can span across the gaps between type constructor vertices and their connection ....

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Karen L. Bernstein and Eugene W. Stark. Debugging Type Errors (Full Version). Technical report, Computer Science Department, State University of New York at Stony Brook, Stony Brook, NY 11794-4400, U.S.A., November 1995. http:// www.cs.sunysb.edu/stark/REPORTS/INDEX.html.

....as there may be several ways to correct the mistake, not all of which may be found by the system. If several are found then it is not possible to pick between them without human input. Other works on helping programmers debug type errors have not resulted in any techniques to transform syntax[Wan86, BS93, BS95, DB96, McA98, McA99, Yan99, YMT01, Chi01]. 1.2 THE THEORY BEHIND THIS SYSTEM Let s look at the example from the introduction. The problem is that the function map has type ( a b) a list b list which means that it takes a function and then a list as curried arguments but has been supplied with its arguments in ....

Karen L. Bernstein and Eugene W. Stark. Debugging Type Errors (Full Version). Technical report, Computer Science Department, State University of New York at Stony Brook, 1995. http://www.cs.sunysb.edu/ stark/REPORTS/INDEX.html.

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Karen L. Bernstein and Eugene W. Stark. Debugging type errors (full version). Technical report, State University of New York at Stony Brook, Computer Science Department, 1995. http://www.cs.sunysb.edu/¸stark/REPORTS/INDEX.html.

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Karen L. Bernstein and Eugene W. Stark. Debugging type errors (full version). Technical report, State University of New York at Stony Brook, Computer Science Department, November 1995. http://www.cs.sunysb.edu/stark/REPORTS/INDEX.html.

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Karen L. Bernstein and Eugene W. Stark. Debugging type errors. Technical report, State University of New York at Stony Brook, Computer Science Department, October 1995. 14

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