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rusty-alto technical overview

rusty-alto is a Rust implementation of weighted tree automata and interpreted regular tree grammars (IRTGs), designed to consume Alto-compatible data while offering a clean compositional API and efficient parsing algorithms.

The main pieces are:

• an oracle-style interface for bottom-up tree automata;
• an explicit, indexed automaton representation;
• lazy automaton combinators;
• algebras, homomorphisms, and IRTG interpretations;
• typed input/output codec registries and algebra-owned display codecs;
• TAG string, TAG derived-tree, and feature-structure algebras;
• materialization and A* algorithms that turn composed automata into parse charts or one-best derivations;
• runners, Viterbi extraction, corpus I/O, and evaluation tools.

Start here:

• Architecture follows data through the main modules.
• Parsing pipeline explains how an IRTG and an input sentence become a derivation.
• Choosing a parsing algorithm compares the user-facing strategies, their trade-offs, and cooperative cancellation.
• Codec infrastructure explains format discovery, algebra value visualization, and the GUI integration boundary.
• Design decisions records the abstractions and performance trade-offs that shape the implementation.
• Development and performance describes the repository layout, testing, benchmarking, and the relationship with Alto and packed-term-arena.

For the public Rust API, see the generated cargo documentation. For command-line usage, see the README and docs/eval.md.