o42a is a high-level general purpose programming language. It is:

  • compiled,
  • statically-typed,
  • prototype-based,
  • logic-driven, and
  • primarily declarative, while
  • the imperative programming style is also supported.

A program written in o42a is closer to natural English text than one written in any C-like programming language.

The language is designed with programming productivity and code maintainability as main priorities. This achieved by

  • powerful, yet restrained, semantics, and
  • expressive and natural syntax.

See the Mission Statement
Take a look at the feature list for overall language description.
Read the documentation for the details.

Development Status

A prototype of compiler is under development. This compiler is written in Java and uses LLVM for executable code generation.

All documented language features are implemented. The development is currently focused on core libraries implementation, compiler stability, and implementation of additional language features necessary to make libraries handy and efficient.

See the detailed development status and plan.

Hello, World!

Here is a “Hello, World!” program written in o42a:

Use namespace 'Console'

@Main (
  Print "Hello, World!" nl

See the explanation.


The o42a compiler and source code are available under the terms of GNU General Public License, version 3 or later.

The run-time libraries and source code are available under the terms of Mozilla Public License, version 2.0.

Proceed to the download section.