Extensible record

Proposals, implementations can be found on the FirstClassLabels page of Haskell' Wiki.

Papers and libraries

• HList --- a Haskell library for strongly typed heterogeneous collections includes also extensible records. Its relatedness to database programming is described in the articles, see also its possible relatedness to HaskellDB project.
• Daan Leijen: First-class labels for extensible rows. See also the description of the Haskell-like language Morrow, it is based on the concepts of the article. And Extensible records with scoped labels: "We describe a natural approach to typing polymorphic and extensible records that is simple, easy to use in practice, and straightforward to implement."
• Simon Peyton Jones and Greg Morrisett: A proposal for records in Haskell
• Mark Jones and Simon Peyton Jones: Lightweight Extensible Records for Haskell
• Mark P. Jones: A prototype implementation of extensible records for Hugs
• Didier Remy's Typing record concatenation for free on Erik Knoop's page
• Benedict R. Gaster, Mark P. Jones: A Polymorphic Type System for Extensible Records and Variants
• Chameleon, a Haskell-like language, see its records

Applications

Declarative database management

Such systems can achieve more type safety (compared to direct SQL handling). They usually formulate a relational algebra concept in a declarative language.

HaskellDB

A problem where some concepts of extensible records could be useful is described in the HaskellDB project. More precisely, the problem is described in the paper downloadable from

• Chalmers version of HaskellDB (see Papers subsection on Documentation)
• which presupposes reading also paper on the Daan Leijen's original HaskellDB page (see Documentation subpage, PostScript version)

HaskellDB uses its own extensible record system, but see also HaskellDB#Future.

CoddFish

CoddFish is another declarative, type safe database system. As for extensible record system, it uses HList --- a Haskell library for strongly typed heterogeneous collections.

Related concepts

Dependent type -- as an explanation for its relatedness here, see Why Dependent Types Matter written by Thorsten Altenkirch, Conor McBride, James McKinna -- or see at least its Conclusions section (section 8, pages 18--19).

Type arithmetic seems to me also a way yielding some tastes from dependent type theory.

Relational algebra implementations usually use extensible records.