MagnusOpera.FScript.Language v0.22.0 — nugetz
MagnusOpera/MagnusOpera.FScript.Languagev0.22.0
✓ 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.
Language Snapshot
FScript currently includes:
- bindings and functions:
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.
- unified brace literals for records/maps (
{ Field = value }, { [key] = value }, {} for empty map), with map keys typed as string or int.
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
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.