Frontend And Compilation

Otter parses JavaScript and TypeScript through OXC. The active frontend stack is:

• crates/otter-syntax: source kind detection, OXC parse options, and parse-once callbacks.
• crates/otter-compiler: AST-to-bytecode lowering and TypeScript erasure.
• crates/otter-bytecode: bytecode module, disassembly, and JSON dump formats.

Do not regex-parse JavaScript or TypeScript source. Consumers that need to inspect module syntax or other AST properties should use otter_syntax::with_program and reuse the parsed OXC program when compiling script sources.

The foundation TypeScript policy is:

• erase type-only constructs such as interface, type, declare, import type, export type, abstract methods, as, satisfies, non-null assertions, and type instantiation syntax;
• reject runtime TypeScript constructs that cannot be erased cleanly in the current engine slice, including enum, runtime namespace, and decorators;
• preserve original source spans through diagnostics and stack traces.

Bytecode dumps are part of the supported CLI/debugging surface:

otter --dump-bytecode path/to/script.js
otter --dump-bytecode=json path/to/script.ts

The text dump starts with:

; otter bytecode dump v1 - module=<specifier> source_kind=<javascript|typescript>

The JSON dump is intended for tools and tests. Keep it stable when possible; when the schema must change, update tests, docs, and any downstream consumers in the same patch.