Polymorphic type inference and assignment

Leroy, Xavier; Weis, Pierre

doi:10.1145/99583.99622

Cited by 55 publications

(55 citation statements)

References 8 publications

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“…- [9] presents a somewhat alternative view: here focus is not on detecting creation of reference cells but rather to detect their use; this means that if an identifier occurs free in a function closure then all variables in its type have to be "examined". This method is quite powerful but unfortunately it fails to be a conservative extension of ML (cf.…”

Section: Introductionmentioning

confidence: 99%

Polymorphic subtyping for effect analysis: The static semantics

Amtoft

Nielson

et al. 1997

Analysis and Verification of Multiple-Agent Languages

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Abstract. The integration of polymorphism (in the style of the ML let-construct), subtyping, and effects (modelling assignment or communication) into one common type system has proved remarkably difficult. One line of research has succeeded in integrating polymorphism and subtyping; adding effects in a straightforward way results in a semantically unsound system. Another line of research has succeeded in integrating polymorphism, effects, and subeffecting; adding subtyping in a straightforward way invalidates the construction of the inference algorithm. This paper integrates all of polymorphism, effects, and subtyping into an annotated type and effect system for Concurrent ML and shows that the resulting system is a conservative extension of the ML type system.

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Section: Introductionmentioning

confidence: 99%

Polymorphic subtyping for effect analysis: The static semantics

Amtoft

Nielson

et al. 1997

Analysis and Verification of Multiple-Agent Languages

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“…If we considered only benchmarks proposed in the literature [10,11], we would come to the conclusion that the relaxed value restriction adds no power: its results exactly matches those of the strict value restriction. This is because all examples in the literature are only concerned with polymorphic procedures, not polymorphic data.…”

Section: Typing Power and Usefulnessmentioning

confidence: 96%

“…As such, this would be sound to make them normal polymorphic variables. Yet more refined type systems, based either on effect analysis by Talpin and Jouvelot [10] or closure typing by Leroy and Weis [11,12], are able to extract this polymorphism, by tracking in more detail creation and access of references. They both give the same type to imp map and an applicative version of map, but this is at the price of adding information about the program execution flow.…”

Section: Conservative Solutionsmentioning

confidence: 99%

Relaxing the Value Restriction

Garrigue

2004

Functional and Logic Programming

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Abstract.Restricting polymorphism to values is now the standard way to obtain soundness in ML-like programming languages with imperative features. While this solution has undeniable advantages over previous approaches, it forbids polymorphism in many cases where it would be sound. We use a subtyping based approach to recover part of this lost polymorphism, without changing the type algebra itself, and this has significant applications.

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“…The static semantics then derives both a type and an effect for an expression, and generalization is then defined relative to those effects. This approach is taken by Damas [1], Leroy and Weis [6], Reynolds [9], Talpin and Jouvelot [10,11], and Wright [13]. A slightly different approach is given by Leroy [5], where type arrows are labelled with types that may occur in references.…”

Section: Comparisons With Other Related Systemsmentioning

confidence: 99%

Standard ML Weak Polymorphism Can Be Sound

Greiner¹

1993

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Adding ML-style references to a Hindley-Milner polymorphic type system is troublesome becausc such a system is unsound with naive polymorphic generalization of reference types. Tofte [12] introduced a distinction between imperative and applicative type variables, such that applicative type variables are never in reference types, that provides a simple static analysis of which type variables may be polymorphically generalized. MacQueen's [7] weak type variables generalize imperative type variables with a counter called a strength. The finer distinction allows a more accurate analysis of when a reference may be created, and thus which type variables may be generalized. Unfortunately, weak polymorphism has been presented only as part of the implementation of the SML/NJ compiler, not as a formal type system. As a result, it is not well understood, as its more subtle points are not well known. Furthermore, while versions of the implementation have repeatedly been shown unsound, the concept has not been proven sound or unsound. We present several formal systems of weak polymorphism, show their connection to the SML/NJ implementation, and show the soundness of most of these systems.

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Polymorphic type inference and assignment

Cited by 55 publications

References 8 publications

Polymorphic subtyping for effect analysis: The static semantics

Polymorphic subtyping for effect analysis: The static semantics

Relaxing the Value Restriction

Standard ML Weak Polymorphism Can Be Sound

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