Exploiting diversity in type checkers for better error messages. (April 2017)

• Record Type: Journal Article
• Authors: Chen, Sheng; Erwig, Martin; Smeltzer, Karl
• Is Part Of: Journal of visual languages & computing. Volume 39(2017)
• Page Start: 10
• Page End: 21
• Publication Date: 2017-04
• Subjects: Type-error diagnosing -- Tool combining; Visual programming languages (Computer science) -- Periodicals; Visual programming (Computer science) -- Periodicals; Programming languages (Electronic computers) -- Semantics -- Periodicals; Langages de programmation visuelle -- Périodiques; Programmation visuelle -- Périodiques; Langages de programmation -- Sémantique -- Périodiques; Programming languages (Electronic computers) -- Semantics; Visual programming (Computer science); Visual programming languages (Computer science); Periodicals; Electronic journals; 005
• DOI: 10.1016/j.jvlc.2016.07.001
• Languages: English
• ISSNs: 1045-926X

Abstract

Abstract: Producing precise and helpful type error messages has been a challenge for the implementations of functional programming languages for over 3 decades now. Many different approaches and methods have been tried to solve this thorny problem, but current type-error reporting tools still suffer from a lack of precision in many cases. Based on the observation that different approaches work well in different situations, we have studied the question of whether a combination of tools that exploits their diversity can lead to improved accuracy. Specifically, we have studied Helium, a Haskell implementation particularly aimed at producing good type error messages, and Lazy Typing, an approach developed previously by us to address the premature-error-commitment problem in type checkers. By analyzing the respective strengths and weaknesses of the two approaches we were able to identify a strategy to combine both tools that could markedly improve the accuracy of reported errors. Specifically, we report an evaluation of 1069 unique ill-typed programs out of a total of 11, 256 Haskell programs that reveals that this combination strategy enjoys a correctness rate of 82%, which is an improvement of 25%/20% compared to using Lazy Typing/Helium alone. In addition to describing this particular case study, we will also report insights we gained into the combination of error-reporting tools in general. Abstract : Highlights: We propose the idea of combining error-reporting tools in complementary ways. We develop a strategy for combining two tools for debugging type errors. Our strategy significantly increases the precision of individual tools. We present an iterative process for deriving combining strategies in general.