https://github.com/olewhalehunter/libra

a lazy interpreter of binary relational algebra
https://github.com/olewhalehunter/libra

Last synced: about 2 months ago
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a lazy interpreter of binary relational algebra

• Host: GitHub
• URL: https://github.com/olewhalehunter/libra
• Owner: olewhalehunter
• License: gpl-3.0
• Created: 2017-09-16T18:22:11.000Z (about 7 years ago)
• Default Branch: master
• Last Pushed: 2017-09-20T02:45:01.000Z (about 7 years ago)
• Last Synced: 2024-04-16T09:11:30.427Z (5 months ago)
• Language: Prolog
• Homepage:
• Size: 51.8 KB
• Stars: 2
• Watchers: 3
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Libra - Lazy Interpreter of Binary Relational Algebra

* What is [Relational Programming](http://cs.adelaide.edu.au/~dwyer/TR95-10_TOC.html)?

* [William E. Byrd on Relational Programming with miniKanren](https://www.youtube.com/watch?v=8gh4Ald4yZQ)

* [Bruce MacLennan, 1983](https://calhoun.nps.edu/bitstream/handle/10945/29066/relationalprogra83012macl.pdf)

"Ordinary programming languages calculate functions. Sometimes a function is inappropriate. For example, 4 has two square roots, +2 and -2, but an ordinary programming language provides a sqrt function that returns only one of the roots. So if we want to find both roots of a quadratic equation, we have to deal with each root separately. In a relational language, we need only to specify one solution, and the program will find both. This is because it will treat sqrt as a binary relation. A binary relation is similar in concept to a function, but can map an argument to any number of values (including zero).

Relations have many uses in computer science. The Z Specification Language makes heavy use of relational algebra notation. One reason is that programs are usually required to establish an input-output relationship, but there are often many outputs that are allowable. For example, a program may be asked to find any solution to a problem, or it may be asked to list all solutions, but in no particular order. A functional specification is bound to specify some particular solution or some particular order. A functional specification is usually an over-specification. "

ported to GNU Prolog from Barry Dwyer's Open Prolog (defunct) source