Reference Work Entry

Encyclopedia of Database Systems

pp 1167-1168


  • Peter M. D. GrayAffiliated withUniversity of Aberdeen


At about the same time that Shipman was developing DAPLEX, Buneman and Frankel proposed the highly influential FQL functional query language [1], based on Backus’s FP functional programming paradigm. A major motivation for this work was that it is in principle possible to combine arbitrary computable functions with stored database functions into a functional query language which is not limited to a predefined set of operators.

FQL was intended for implementation over existing DBMSs and an abstract implementation based on the lazy evaluation of stream data was described. In later publications [2,3], FQL was extended with features from the functional programming language ML. In this version, function definition is simpler than in the variable-free FP-like syntax and new higher-order functions can be defined in addition to the built-in ones. Also a set of built-in metalevel functions is provided, as in EFDM. Thus, object-level querying and meta level querying can be car ...

This is an excerpt from the content