MagnusOpera.FScript.Language v0.7.0 — nugetz
MagnusOpera/MagnusOpera.FScript.Languagev0.7.0
✓ Verified.NET Std2.1
Embeddable FScript language engine: parser, type inference, and evaluator.
Get Started
$ dotnet add package MagnusOpera.FScript.LanguageReadme
FScript
FScript is a lightweight, embeddable interpreter with an F#/ML-style language.
It is designed for host applications that need:
- a concise functional scripting language,
- strong static checks (Hindley-Milner type inference),
- controlled host extensibility,
- and a clear sandbox/security boundary.
Why FScript
- F#/ML lineage: immutable data, expressions-first style, pattern matching,
let/fun, algebraic modeling.
- Interpreter pipeline: lexer -> parser -> type inference -> evaluator.
- Host-first extensibility: add external functions with explicit type schemes and runtime implementations.
- Security-aware embedding: script capabilities are defined by what the host exposes.
Language Snapshot
FScript currently includes:
let, let rec, and mutual recursion, lambdas,control flow: if/elif/else, match, for ... in ... do,data: list, option, tuple, map, record, discriminated unions,pattern matching: list, option, tuple, record, union cases,optional type annotations on parameters,type declarations: records and unions (including recursive forms),interpolation, pipeline operator, typeof type tokens, and nameof identifier tokens for host workflows.Quick Start
Build
make build
Test
make test
Run a script
dotnet run --project src/FScript -- samples/types-showcase.fss
Optional sandbox root override:
dotnet run --project src/FScript -- --root /tmp/sandbox samples/types-showcase.fss
samples/types-showcase.fsssamples/patterns-and-collections.fsssamples/tree.fsssamples/mutual-recursion.fss
Installation
CLI via Homebrew
brew install magnusopera/tap/fscript
Embeddable language via NuGet
MagnusOpera.FScript.LanguageMagnusOpera.FScript.Runtime
Interpreter Architecture
The core engine lives in src/FScript.Language and runs in four stages:
- Lexing: indentation-aware tokenization.
- Parsing: AST construction with expression/layout rules.
- Type inference: Hindley-Milner inference + unification + optional annotations.
- Evaluation: typed AST evaluation with immutable values and pattern matching.
Host integration lives in src/FScript.Runtime.
Extensibility Model
FScript is extended through host-provided externs.
- a public name (for script calls),
- a type scheme,
- arity,
- implementation.
Built-in extern families include List.*, Map.*, Option.*, Fs.*, Json.*, Xml.*, Regex.*, hashing, GUIDs, and print.
Sandbox and Security
FScript runs in-process. Security is capability-based:
- scripts can only do what exposed externs allow,
- core language evaluation is deterministic over in-memory values,
- side effects and external I/O are controlled at host extern boundaries.
Operational controls (timeouts, cancellation, resource limits, process/container isolation) are host responsibilities.
Documentation
License
This project is licensed under the MIT License.
See LICENSE.