Type classes in functional logic programming

Martin-Martin, Enrique

doi:10.1145/1929501.1929524

Cited by 7 publications

(5 citation statements)

References 26 publications

(54 reference statements)

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“…A first step towards the specification of the translation of type classes has been already developed in Martin-Martin (2011). -Despite of the lack of principal types, some work on type inference can be done, in the spirit of Schrijvers et al (2009).…”

Section: Discussionmentioning

confidence: 99%

“…Type classes are usually implemented by means of a source-to-source transformation that introduces extra parameters -called dictionaries -to overloaded functions (Hall et al 1996;Wadler and Blott 1989). However, this classical translation produces a problem of missing answers when applied to FLP due to a bad interaction between non-determinism and the call-time choice semantics (Lux 2009;Martin-Martin 2011). Using type-indexed functions and type witnesses -a representation of types as values -it is possible to develop a type-passing translation for type classes similar to Thatté (1994) that solves this problem and whose translated programs are well-typed in the proposed liberal type system.…”

Section: Type-indexed Functionsmentioning

confidence: 99%

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A liberal type system for functional logic programs

López-Fraguas¹,

Martin-Martin²,

Rodríguez-Hortalá³

2014

Math. Struct. Comp. Sci.

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We propose a new type system for functional logic programming which is more liberal than the classical Damas-Milner usually adopted, but it is also restrictive enough to ensure type soundness. Starting from Damas-Milner typing of expressions, we propose a new notion of well-typed program that adds support for type-indexed functions, a particular form of existential types, opaque higher-order patterns and generic functions -as shown by an extensive collection of examples that illustrate the possibilities of our proposal. In the negative side, the types of functions must be declared, and therefore types are checked but not inferred. Another consequence is that parametricity is lost, although the impact of this flaw is limited as 'free theorems' were already compromised in functional logic programming because of non-determinism. † This work has been partially supported by the Spanish projects STAMP (TIN2008-06622-C03-01), Prometidos-CM (S2009TIC-1465) and GPD (UCM-BSCH-GR35/10-A-910502). † As mentioned in Section 1, patterns in our setting (both first and higher order patterns) are treated in a purely syntactic way, so syntactic unification is used instead of more complex HO unification procedures.

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Section: Discussionmentioning

confidence: 99%

Section: Type-indexed Functionsmentioning

confidence: 99%

A liberal type system for functional logic programs

López-Fraguas¹,

Martin-Martin²,

Rodríguez-Hortalá³

2014

Math. Struct. Comp. Sci.

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“…This is not a principle restriction of our approach but due to the current type system of Curry. If the base language supports overloading (like Haskell or an extension of Curry with type classes [23]), the preprocessor can generate a call to an overloaded CDBI operation. Another option is a complete re-implementation of the type inference of the base language in the SQL preprocessor (as done in [25]).…”

Section: Structure Of the Implementationmentioning

confidence: 99%

A Typeful Integration of SQL into Curry

Hanus¹,

Krone²

2017

Electron. Proc. Theor. Comput. Sci.

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We present an extension of the declarative programming language Curry to support the access to data stored in relational databases via SQL. Since Curry is statically typed, our emphasis on this SQL integration is on type safety. Our extension respects the type system of Curry so that run-time errors due to ill-typed data are avoided. This is obtained by preprocessing SQL statements at compile time and translating them into type-safe database access operations. As a consequence, the type checker of the Curry system can spot type errors in SQL statements at compile time. To generate appropriately typed access operations, the preprocessor uses an entity-relationship (ER) model describing the structure of the relational data. In addition to standard SQL, SQL statements embedded in Curry can include program expressions and also relationships specified in the ER model. The latter feature is useful to avoid the error-prone use of foreign keys. As a result, our SQL integration supports a high-level and type-safe access to databases in Curry programs.Comment: In Proceedings WLP'15/'16/WFLP'16, arXiv:1701.0014

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“…Type classes are usually implemented by means of a source-to-source transformation that introduces extra parameters-called dictionaries-to overloaded functions (Wadler and Blott, 1989;Hall et al, 1996). However, this classical translation produces a problem of missing answers when applied to FLP due to a bad interaction between non-determinism and the call-time choice semantics (Lux, 2009;Martin-Martin, 2011). Using type-indexed functions and type witnesses-a representation of types as values-it is possible to develop a type-passing translation for type classes similar to (Thatté, 1994) that solves this problem and whose translated programs are well-typed in the proposed liberal type system.…”

Section: Type-indexed Functionsmentioning

confidence: 99%