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Version: 0.60.1

F# Type Provider and Use Cases

If your host is F#, the FScript type provider gives a strongly-typed bridge from script exports to F# calls.

What it gives you​

The provider can:

  • parse and type-check .fss scripts at compile time,
  • expose [<export>] functions as typed static members,
  • fail fast when runtime script signatures drift from compile-time expectations.

This is useful when you want dynamic script behavior without giving up compile-time safety in the host codebase.

Package​

Core model​

Provider entrypoint namespace/type:

  • Namespace: FScript.TypeProvider
  • Type provider: FScriptScriptProvider

Static parameters:

  • ScriptPath (required)
  • RootDirectory (optional)
  • ExternProviders (optional)

Minimal usage shape (F#)​

open FScript.TypeProvider

type BuildScript =
  FScriptScriptProvider<
    ScriptPath = "scripts/build.fss",
    RootDirectory = "."
  >

let result = BuildScript.run "release"

BuildScript.run above is generated from an [<export>] let run ... function in the script.

Runtime override pattern​

For advanced scenarios, the provider supports runtime source overrides via resolver hooks.

  • SetRuntimeResolver
  • ClearRuntimeResolver

This lets you switch script source dynamically (for example by tenant/environment) while preserving signature compatibility checks.

Real-world use cases​

1) Product rules with safe host calls​

Use scripts for business rules (pricing, routing, eligibility), but call them from typed F# methods generated by the provider.

Benefit:

  • script flexibility for domain teams,
  • compile-time confidence for app developers.

2) Plugin-like behavior without reflection-heavy plumbing​

Expose plugin functions via [<export>] and call them as typed members instead of late-bound string dispatch.

Benefit:

  • simpler host code,
  • less runtime casting/shape checking logic.

3) CI gate for script contract drift​

Provider checks script exports at compile time. If script shape changes in a breaking way, the host build fails early.

Benefit:

  • breakages are discovered in CI, not in production.

4) Environment-specific script resolution​

Use runtime resolver override to serve different script sources (dev/staging/prod, tenant-specific variants) while enforcing exported signature compatibility.

Benefit:

  • controlled dynamic behavior with a strong compatibility contract.

When to use provider vs ScriptHost​

Use type provider when:

  • host is F#,
  • you want strongly-typed generated members,
  • compile-time validation of script exports is a priority.

Use ScriptHost directly when:

  • host is not F#,
  • you need explicit runtime loading/invocation control,
  • you prefer manual dynamic dispatch.