Agda (programming language)
Agda is a dependently typed functional programming language originally developed by Ulf Norell at Chalmers University of Technology with implementation described in his PhD thesis. The original Agda system was developed at Chalmers by Catarina Coquand in 1999. The current version, originally known as Agda 2, is a full rewrite, which should be considered a new language that shares a name and tradition.
| Paradigm | Functional |
|---|---|
| Designed by | Ulf Norell; Catarina Coquand (1.0) |
| Developer | Ulf Norell; Catarina Coquand (1.0) |
| First appeared | 2007 (1.0 in 1999) |
| Stable release | 2.6.3
/ January 30, 2023 |
| Typing discipline | strong, static, dependent, nominal, manifest, inferred |
| Implementation language | Haskell |
| OS | Cross-platform |
| License | BSD-like |
| Filename extensions | .agda, .lagda, .lagda.md, .lagda.rst, .lagda.tex |
| Website | wiki |
| Influenced by | |
| Coq, Epigram, Haskell | |
| Influenced | |
| Idris | |
Agda is also a proof assistant based on the propositions-as-types paradigm, but unlike Coq, has no separate tactics language, and proofs are written in a functional programming style. The language has ordinary programming constructs such as data types, pattern matching, records, let expressions and modules, and a Haskell-like syntax. The system has Emacs, Atom, and VS Code interfaces but can also be run in batch mode from the command line.
Agda is based on Zhaohui Luo's unified theory of dependent types (UTT), a type theory similar to Martin-Löf type theory.
Agda is named after the Swedish song "Hönan Agda", written by Cornelis Vreeswijk, which is about a hen named Agda. This alludes to the name of the theorem prover Coq, which was named after Thierry Coquand.