Overview

OpenCog Hyperon is a substantially revised, novel version of OpenCog - which is currently at an active pre-alpha stage of development and experimentation. One of the focuses in the Hyperon design is a successor to the OpenCog Classic Atomese language with clear semantics supporting meta-language features, different types of inference, etc. What we have landed on is an "Atomese 2" language called MeTTa (Meta Type Talk).

In order to get familiar with MeTTa one can read MeTTa specification and watch video with different MeTTa example explained. The examples of MeTTa programs can be found in ./python/tests/scripts directory. Please look at the Python unit tests to understand how one can use MeTTa from Python. More complex usage scenarios are located at MeTTa examples repo. A lot of different materials can be found on OpenCog wiki server.

If you want to contribute the project please see the contribution guide first. If you find troubles with the installation, see the Troubleshooting section below. For development related instructions see the development guide.

Using the latest release version

It is the most simple way of getting MeTTa interpreter especially if you are a Python developer. The following command installs the latest release version from PyPi package repository:

python3 -m pip install hyperon

Prepare development environment

Docker

A docker image can be used as a ready to run stable and predictable development environment. Please keep in mind that resulting image contains temporary build files and takes a lot of a disk space. It is not recommended to distribute it as an image for running MeTTa because of its size.

Ready to use image

Run latest docker image from the Dockerhub:

docker run -ti trueagi/hyperon:latest

Build image

Docker 26.0.0 or greater version is required.

Build Docker image from a local copy of the repo running:

docker build -t trueagi/hyperon .

Or build it without cloning the repo running:

docker build \
    --build-arg BUILDKIT_CONTEXT_KEEP_GIT_DIR=1 \
    -t trueagi/hyperon \
    http://github.com/trueagi-io/hyperon-experimental.git#main

Run the image:

docker run --rm -ti trueagi/hyperon

If the docker image doesn't work, please raise an issue.

Manual installation

Prerequisites

• Install the latest stable Rust, see Rust installation page. Make sure your PATH variable includes $HOME/.cargo/bin directory after installing Rust (see the Notes at the installation page).

  Requirements for building C and Python API

  • Python3 and Python3-dev (3.7 or later)
  • Pip (23.1.2 or later)
  • GCC (7.5 or later)
  • CMake (3.15 or later)

• Install cbindgen:

cargo install --force cbindgen

• Install Conan and make default Conan profile:

python3 -m pip install conan==1.62
conan profile new --detect default

• Upgrade Pip to the required version:

python3 -m pip install pip==23.1.2

Build and run

Rust library and REPL

Build and test the Rust binaries:

cargo test

The experimental features can be enabled by editing Cargo.toml file before compilation or by using --features command line option. See comments in the [features] section of the file for the features descriptions. For example to turn on minimal MeTTa interpreter one can add "minimal" to default in Cargo.toml

Run examples:

cargo run --example sorted_list

Run Rust REPL:

cargo run --features no_python --bin metta

You can also find executable at ./target/debug/metta.

To enable logging during running tests or examples export RUST_LOG environment variable:

RUST_LOG=hyperon=debug cargo test

Running benchmarks requires nightly toolchain so they can be run using:

cargo +nightly bench

Generate docs:

cargo doc --no-deps

Docs can be found at ./target/doc/hyperon/index.html.

C and Python API

Setup build:

mkdir -p build
cd build
cmake ..

To run release build use -DCMAKE_BUILD_TYPE=Release cmake flag.

Build and run tests:

make
make check

Running Python and MeTTa examples

In order to run examples you need to install the Python module. Please ensure you built C and Python API first. Then execute the following command in the top directory of repository:

python3 -m pip install -e ./python[dev]

After this one can run unit tests within python directory using pytest:

pytest ./tests

One can run MeTTa script from command line:

metta ./tests/scripts/<name>.metta

Run REPL:

cargo run --bin metta

You can also find executable at ./target/debug/metta.

Logger

You can enable logging by prefixing the metta command line by

RUST_LOG=hyperon[::COMPONENT]*=LEVEL

where

• [::COMPONENT]* is a, possibly empty, sequence of modules and submodules of hyperon, such as ::metta, ::metta::runner, ::common, ::common::multitrie, etc.
• LEVEL is the log level. Possible log levels are: error, warn, info, debug and trace.

For example, to log all hyperon messages at the debug level and below, while running script.metta, you may type:

RUST_LOG=hyperon=debug metta script.metta

Or, to log all hyperon messages at the trace level and below, restricted to module metta and submodule types, you may type:

RUST_LOG=hyperon::metta::types=trace metta script.metta

By default all log messages are directed to stderr.

Troubleshooting

Conan claims it cannot find out the version of the C compiler

If you see the following cmake output:

ERROR: Not able to automatically detect '/usr/bin/cc' version
ERROR: Unable to find a working compiler
WARN: Remotes registry file missing, creating default one in /root/.conan/remotes.json
ERROR: libcheck/0.15.2: 'settings.compiler' value not defined

Try to create the default Conan profile manually:

conan profile new --detect default

If it doesn't help, then try to manually add compiler, compiler.version and compiler.libcxx values in the default Conan profile (~/.conan/profiles/default). For example:

conan profile update settings.compiler=gcc default
conan profile update settings.compiler.version=7 default
conan profile update settings.compiler.libcxx=libstdc++ default

Rust compiler shows errors

Please ensure you are using the latest stable version:

rustup update stable

Importing hyperon Python module fails

If importing the hyperon module in Python

import hyperon

returns the error:

ModuleNotFoundError: No module named 'hyperonpy'

Please ensure you have installed the Python module, see Running Python and MeTTa examples.

Development

Structure of the codebase

Main library libhyperon.rlib is written in Rust language, it contains core API which can be used from other Rust projects. Source code of the library is located under ./lib directory. It is a plain Rust project which can be built and tested using Cargo tool.

In order to provide API for platforms and languages other than Rust there is a C API export library libhyperonc. Source code of the library is located under ./c directory. The library contains Rust C API bindings and depends on libhyperon.rlib library. Native library is compiled using Cargo, C headers are generated using cbindgen tool.

Source code of the Python integration library is located under ./python directory. It contains two main parts. First part is a native Python library libhyperonpy which is written using pybind11, it converts Python API calls into C API calls and vice versa. Second part is a Python library hyperon which uses libhyperonpy as a proxy for a C API calls.

All components which depend on libhyperonc are built using CMake build tool in order to manage dependencies automatically.

The diagram below demonstrates main components and dependencies between them: Source code of the diagram

Language support for IDEs

Different IDEs may require different tweaks to support the languages used in the codebase. The language servers which we use for development are:

• rust-analyzer;
• clangd, generate compile commands for the clangd using cmake variable:

  cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=Y ..
  

• Python LSP server.