ReoScript

ReoScript is an ECMAScript-like scripting engine for .NET applications. It is designed for embedding, so host applications can execute user-defined scripts, expose application objects to scripts, and optionally allow direct access to .NET types, members, and events.

The current migrated solution targets .NET 10 and contains:

• Source/ReoScript/: the core scripting library
• Source/ReoScriptRunner/: a command-line runner for .reo files
• Source/TestCase/: xUnit-based language and engine tests

Highlights

• JavaScript-like syntax with ReoScript-specific extensions
• Embed scripts into .NET applications through ScriptRunningMachine
• Pass host values into scripts as globals
• Register native C# functions callable from script
• Optional direct access to .NET objects and imported CLR types
• Closures, lambda expressions, JSON, modules, and timer-based async callbacks
• Extra language features such as object merge, object spread, destructuring, and tag-style syntax

Documentation

• English User Guide
• Japanese User Guide

Quick Start

Build the solution:

dotnet build Source/ReoScript.sln

Run the CLI runner:

dotnet run --project Source/ReoScriptRunner -- sample.reo
dotnet run --project Source/ReoScriptRunner -- -e "console.log(1 + 2)"
dotnet run --project Source/ReoScriptRunner -- -console

Minimal embedding example:

using unvell.ReoScript;

var srm = new ScriptRunningMachine();

srm.SetGlobalVariable("appName", "Demo");
srm.Run(@"
function add(a, b) {
  return a + b;
}
");

var result = srm.CalcExpression("add(10, 20)");

Minimal script example:

var total = 0;

for (var i = 1; i <= 10; i++) {
  total += i;
}

console.log(total);

Build

Build all migrated projects:

dotnet build Source/ReoScript.sln

Release build:

dotnet build Source/ReoScript.sln -c Release

Test

Run all tests:

dotnet test Source/ReoScript.sln

Run the test project directly:

dotnet test Source/TestCase/TestCase.csproj

Run a filtered test:

dotnet test Source/TestCase/TestCase.csproj --filter "DisplayName~closure"

The test project covers:

• XML-driven language tests under Source/TestCase/tests/
• CLR interop tests
• engine-level tests for loop protection, module loading, truthy/falsy rules, async timers, and error reporting

Repository Layout

Main migrated projects:

• Source/ReoScript/
  • core engine library targeting net10.0
  • assembly name: unvell.ReoScript
• Source/ReoScriptRunner/
  • CLI runner targeting net10.0
  • assembly name: ReoScript
• Source/TestCase/
  • xUnit test project targeting net10.0

Additional directories:

• Samples/: sample host applications and embedding examples
• docs/: end-user documentation
• Source/ReoScript/scripts/: embedded built-in ReoScript libraries such as core.reo, array.reo, debug.reo, and number.reo

Not yet migrated into the current .NET 10 solution:

• Source/ReoScriptEditor/
• Source/ReoScriptExtensions/

Language Overview

ReoScript is close to JavaScript, but it is not a drop-in JavaScript runtime. Supported and tested areas include:

• variable declarations with var
• if, for, while, switch, try/catch/finally
• functions, lambdas, lexical closures
• objects, arrays, JSON, eval, typeof, instanceof
• truthy/falsy conditional semantics
• modules through import, import ... as, and importModule(...)
• async timers via setTimeout, setInterval, and clearInterval

ReoScript-specific extensions include:

• object merging with a + b
• new Type() { ... } style object initialization
• shorthand properties, object spread, and destructuring support
• tag-style syntax such as <User />

For full syntax and usage details, use the guides in the docs/ directory.

Embedding Features

The main host integration surface is ScriptRunningMachine.

Typical host-side operations:

• execute script text with Run(...)
• evaluate expressions with CalcExpression(...)
• expose values with SetGlobalVariable(...)
• read globals back with GetGlobalVariable(...)
• import CLR types with ImportType(...)
• import namespaces with ImportNamespace(...)
• create isolated module objects with ImportModuleFile(...)

Feature gates are controlled through MachineWorkMode, including:

• AllowDirectAccess
• AllowImportTypeInScript
• AllowCLREventBind

For examples, see:

• Samples/NativeFunctionExtension/
• Samples/DirectAccess/
• Samples/CLRTypeImporting/
• Samples/ConsoleRunner/

Safety and Runtime Behavior

ReoScript includes several runtime behaviors that matter for hosts:

• MaxIterationsPerLoop protects against runaway for and while loops
• module imports are cached
• async callback and event-handler exceptions can be observed through ScriptError
• WorkPath controls relative script import resolution

Samples

The Samples/ directory contains example integrations, including:

• console execution
• native function extension
• direct access to host objects
• CLR type importing
• property getter/setter integration
• script editor and UI-based demos

License

MIT License

Copyright (c) UNVELL Inc., Jingwood 2012-2026, All Rights Reserved.