@magnusopera/fscript

Embeddable FScript language engine: parser, type inference, and evaluator.

This package exposes parser, inference, evaluation, exported-function invocation, REPL-like sessions, virtual imports, and JS-provided externs for Node and browser-compatible ESM hosts.

Provide complete environments with registration({types, unions, functions}) and pass them as {registration: environment}. HostTypes.describe declares visible fields; scriptConstructible: true enables ordinary script records, while the default retains an opaque JavaScript payload through HostTypes.wrap / unwrap. HostTypes.describeUnion, wrapUnion, and unwrapUnion support registered nominal cases. T.named(name) references those types in signatures.

HostFunctions.create({name, parameters, result, invoke}) builds a typed function from explicit script types. Handlers receive tagged arguments and an invocation context with apply for synchronous script callbacks. Existing extern declarations still work. Fable task execution and Promise-returning handlers are unsupported.

See the JavaScript hosting reference for descriptor tables and examples. Run the local sample after building: node examples/hosting.mjs.