Implementing type classes

PetersonJohn,; JonesMark,

doi:10.1145/173262.155112

Cited by 9 publications

(5 citation statements)

References 6 publications

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“…The translation of type classes was a popular topic in the early 90's [10,25,2,35]. Since then, type classes have been employed in many applications way beyond their original purpose.…”

Section: Resultsmentioning

confidence: 99%

Extracting programs from type class proofs

Sulzmann

2006

Proceedings of the 8th ACM SIGPLAN International Conference on Principles and Practice of Declarative Programming

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Standard presentations of type class translation schemes exhibit some surprising problems when translating Haskell 98 programs. We suggests ways how to fix these problems based on a formal framework for extracting programs from type class proofs. Our description includes type improvement and recursive dictionaries -something which has not been formally studied before. Thus, we are able to advance the state of art of translating type classes and open up the possibility for new type class applications.

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“…The translation of type classes was a popular topic in the early 90's [10,25,2,35]. Since then, type classes have been employed in many applications way beyond their original purpose.…”

Section: Resultsmentioning

confidence: 99%

Extracting programs from type class proofs

Sulzmann

2006

Proceedings of the 8th ACM SIGPLAN International Conference on Principles and Practice of Declarative Programming

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“…There are some features we support indirectly by allowing them in the "opaque" regions of the datatype which Ghostbuster-generated code need not traverse, but we do not model explicitly in our core language. This currently includes type families (Chakravarty et al, 2005;Schrijvers et al, 2008) and typeclasses (Peterson & Jones, 1993;Hall et al, 1996).…”

Section: Runtime Type Representationmentioning

confidence: 99%

Ghostbuster: A tool for simplifying and converting GADTs

Zakian¹,

McDonell²,

Cimini³

et al. 2018

J. Funct. Prog.

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Generalized Algebraic Data Types, or simply GADTs, can encode non-trivial properties in the types of the constructors. Once such properties are encoded in a datatype, however, all code manipulating that datatype must provide proof that it maintains these properties in order to typecheck. In this paper, we take a step toward gradualizing these obligations. We introduce a tool, Ghostbuster, that produces simplified versions of GADTs which elide selected type parameters, thereby weakening the guarantees of the simplified datatype in exchange for reducing the obligations necessary to manipulate it. Like ornaments, these simplified datatypes preserve the recursive structure of the original, but unlike ornaments, we focus on information-preserving bidirectional transformations. Ghostbuster generates type-safe conversion functions between the original and simplified datatypes, which we prove are the identity function when composed. We evaluate a prototype tool for Haskell against thousands of GADTs found on the Hackage package database, generating simpler Haskell'98 datatypes and round-trip conversion functions between the two.

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“…Passing a dictionary to perform selection at run-time is unnecessary. Full laziness and common subexpression elimination are techniques used to avoid repeated construction of dictionaries at run-time [2,3,27,28], but the optimization could be avoided a priori. This and related implementation issues are however outside of the scope of this paper and are left for further work.…”

Section: Semanticsmentioning

confidence: 99%