engine

Foundation types for every pluggable engine: Term, Model, and the arena view.

What it is

The substrate every other engine-* crate builds on. It defines the Term algebra used to express eval schemes, the Model trait an engine implements, and a minimal, object-safe arena view (AstRef / AstNode / LanguageView) that lets a model inspect an AST without depending on handl-language — which would be a dependency cycle, since handl-language already depends on hnl-engine for Term.

Modules

• term — Term, ArrSource, Side, RewriteWitness, handler elimination
• term_data — TermData — the owned, inspectable form of a term
• term_interpreter — interpret — the generic scheme interpreter
• nbe — normalization-by-evaluation helpers shared by the typecheckers

Start here

• Reference — public API
• How-to — task recipes
• Explanation — design and rationale

No tutorials: this repo is a building block used from Rust. End-to-end walkthroughs live with the product that composes it — see the Handl platform.