Website contains:

• Development blogs which are written for general audience
• Installation instructions (basically telling you what to download in GitHub Releases)
• Tutorial for functional programming features
• Tutorial for theorem proving features

Warning

Aya is under active development, so don't be surprised about bugs, usability or performance issues (please file issues or create threads in discussions!), but we have the goal to make it as user-friendly as we can feasibly do.

What to expect?

• Dependent types, including Π-types, Σ-types, indexed families, etc. You could write a sized-vector type.
• Set-level cubical type theory (XTT).
  • Demonstration of quotient-inductive-inductive types, no forward declaration or mutual block needed! We infer the type checking order by how definitions use each other.
  • Proof of funExt in paths.aya.
• Pattern matching with first-match semantics. Checkout the red-black tree (without deletion yet).
• A JIT-compiler that translates Aya code to higher-order abstract syntax in Java. This makes the interpreter to run tree-sort 10x faster! See benchmark code.
• Overlapping and order-independent patterns. Very useful in theorem proving.
• A literate programming mode with inline code fragment support, inspired from Agda and 1lab. You may preview the features (in Chinese) here.
• Binary operators, with precedence specified by a partial ordering (instead of a number like in Haskell or Agda).
• A fairly good termination checker. We adapted some code from Agda's implementation to accept more definitions such as the testSwapAdd example in this file (which are rejected by, e.g. Arend).

See also use as a library.

Contributing to Aya

See HACKING.md for technical details, CONTRIBUTING.md for social responsibilities, and CODE_OF_CONDUCT.md.

Questions are always welcomed in Discussion. We will try our best to answer your questions. Please be nice to us! We also welcome nitpicks on any user-interaction issues, especially on error reporting. Let us know if you have any suggestions.

Use as a library

It's indexed in mvnrepository, and here are some example build configurations:

<!-- Maven -->
<dependency>
    <groupId>org.aya-prover</groupId>
    <artifactId>[project name]</artifactId>
    <version>[latest version]</version>
</dependency>

// Gradle
implementation group: 'org.aya-prover', name: '[project name]', version: '[latest version]'

• [project name] specifies the subproject of Aya you want to use, and the options are pretty, base, cli-impl, parser, etc.
  • The syntax definitions live in syntax.
  • The parser lives in parser (the generated parsing code) and producer (transformer from parse tree to concrete syntax tree).
  • The type checker lives in base.
  • The JIT compiler lives in jit-compiler.
  • The generalized pretty printing framework is in pretty.
  • The library system, literate mode, single-file type checker, and basic REPL are in cli-impl.
  • The generalized tree builder, generalized termination checker, and a bunch of other utilities (files, etc.) are in tools.
  • The generalized binary operator parser, generalized mutable graph are in tools-kala because they depend on a larger subset of the kala library.
  • The command and argument parsing framework is in tools-repl. It offers an implementation of jline3 parser based on Grammar-Kit and relevant facilities.
  • The literate-markdown related infrastructure is in tools-md. It offers JetBrains/markdown extensions for literate mode of any language with a highlighter.
• [latest version] is what you see on this badge .