MeTTa Overview

MeTTa (Meta Type Talk) is the primary programming and knowledge representation language for the OpenCog Hyperon framework. It is specifically designed to meet the requirements of Artificial General Intelligence.

Why MeTTa?

Standard programming languages (like Python or C++) are designed for efficient execution of fixed algorithms. They are not ideally suited for:

1. Dynamic Knowledge Representation: Storing self-modifying, uncertain knowledge.
2. Meta-Reasoning: Programs that can easily reason about and rewrite their own code.
3. Neuro-Symbolic Integration: Coherently mixing neural activations with symbolic rules.

MeTTa is designed from the ground up to solve these problems.

Core Characteristics

1. Atom-Centric

In MeTTa, there is no distinction between "code" and "data." Everything is an Atom. This property, called homoiconicity, allows the system's reasoning engines to manipulate program logic as easily as they manipulate facts.

2. Pattern Matching as Computation

Unlike imperative languages where you give a sequence of commands, MeTTa "computes" by transforming Atoms through pattern matching and rewriting rules.

3. Gradual Typing

MeTTa supports a flexible type system. You can have untyped code for rapid exploration and strictly typed code for formal verification and optimization.

4. Multi-Paradigm

MeTTa naturally supports:

• Functional Programming: via mapping and reduction.
• Logic Programming: similar to Prolog but more flexible.
• Probabilistic Programming: handling uncertain truth values.

How it Connects to Hyperon

MeTTa is the interface to the AtomSpace. When you write MeTTa code, you are effectively creating and manipulating Atoms in the hypergraph database. The Pattern Matcher and PLN reasoner are invoked directly from within MeTTa scripts.

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Next: MeTTa Syntax