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Introduction

FScript is a lightweight, embeddable programming language with an F#/ML-style syntax and a host-first runtime model.

This manual is intentionally language-first: it starts by teaching script writing, then moves into host integration and advanced reference material.

What FScript is for​

FScript is designed for applications that need:

  • a compact scripting language for user or internal automation,
  • static checks before execution (type inference),
  • expression-oriented code with strong pattern matching,
  • explicit control over capabilities exposed to scripts.

In practice, this makes FScript a good fit for embedded scripting in tools, automation platforms, build systems, and domain-specific workflows where safety and predictability matter.

What this manual teaches​

By the end of this manual, you should be comfortable with:

  • writing and running .fss scripts,
  • modeling data with records, unions, lists, maps, and options,
  • using pattern matching for clear control flow,
  • using the standard library effectively,
  • exposing host functions (externs) when embedding FScript.

Why FScript​

  • Expression-first language design.
  • Static type inference (Hindley-Milner style).
  • Strong pattern matching.
  • Host-controlled capabilities through extern functions.

Suggested learning path​

  1. Start with Quickstart to install and run your first script.
  2. Continue with Language Fundamentals and work through Language chapters in order.
  3. Use Examples to practice complete script patterns.
  4. Study Stdlib to learn the built-in modules in depth.
  5. Move to Embedding when you need host integration.

Manual structure​

  • Learn: onboarding and first working scripts.
  • Language: core syntax, data modeling, typing, imports/exports, layout rules.
  • Examples: practical scripts and reusable patterns.
  • Embedding: host integration model, extern registration, safety boundaries.
  • Stdlib: detailed function-by-function reference and recipes.
  • Reference: CLI usage and quick lookup material.