Tewelde.FuncScript 0.1.5

FuncScript

FuncScript is a .NET-first expression language and runtime that lets you embed concise, functional business logic inside your applications. It ships with a parser, evaluator, formatter, CLI, unit tests, and optional SQL/GIS helpers, making it straightforward to evaluate custom scripts, map data, or compute derived values at runtime.

Highlights

• Expression-oriented language with blocks, lambdas, pattern-like switches, string templates, lists, and key-value collections.
• Batteries-included standard library covering math, logic, text, list processing, OS helpers, HTML utilities, and JSON conversion.
• Ergonomic .NET embedding via FuncScript.Engine.Evaluate(...), strongly-typed error reporting, and deterministic formatting utilities.
• Extensible through custom IFsFunction implementations or ad-hoc variables injected with DefaultFsDataProvider.
• Extra packages for SQL Server and NetTopologySuite geometries, plus an experimental JavaScript interpreter port.

Repository Layout

• FuncScript/ - core library targeting .NET 6.0; contains the parser, runtime, standard library, and data model.
• FuncScript.Cli/ - minimal .NET 8 CLI (funcscriptcli) that evaluates expressions from the command line.
• FuncScript.Example/ - interactive console sample that demonstrates the REPL-style usage of the runtime.
• FuncScript.Sql/ - optional extension with SQL/geometry helpers and type normalization for ADO.NET results.
• FuncScript.Test/ - NUnit-based test suite covering parsing, evaluation, errors, and formatting.
• js-port/ - in-progress JavaScript port plus editor experiments and examples.

Quick Start

Prerequisites

Install the .NET 8 SDK (includes the .NET 6 tooling required by the library projects).

Build Everything

dotnet restore FuncScript.sln
dotnet build FuncScript.sln

Try the CLI

# Evaluate a simple expression
dotnet run --project FuncScript.Cli -- "(2 + 3) * 4"

# Evaluate a block with variables and built-in helpers
dotnet run --project FuncScript.Cli -- "{ rate:0.13; net:(gross)=>gross*(1-rate); return net(12500); }"

Embed in Your Application

using System;
using System.Collections.Generic;
using FuncScript;
using FuncScript.Model;

var globals = new DefaultFsDataProvider(new List<KeyValuePair<string, object>>
{
    new KeyValuePair<string, object>("taxRate", 0.15),
    new KeyValuePair<string, object>("format", (Func<object,string>)(value => string.Format("{0:#,#0.00}", value)))
});

var expression = "{ net:(gross)=>gross*(1-taxRate); return format(net(gross)); }";
var context = new ObjectKvc(new { gross = 5200 });
var result = FuncScript.Engine.Evaluate(new KvcProvider(context, globals), expression);

var output = new StringBuilder();
FuncScript.Engine.Format(output, result);
Console.WriteLine(output);

The runtime normalizes .NET values so that primitive types, lists, key-value collections, GUIDs, byte arrays, and even delegates translate seamlessly to script data.

Language at a Glance

Script files are case-insensitive and expression-oriented. Common constructs include:

• Blocks: { items:[1,2,3]; return Sum(items); }
• Lambdas: (x)=>x*x or (row, index)=>{ ... }
• String templates: f"Hello {name}!"
• Collections: Lists [1, 2, 3] and records {name:"Ada", skills:["math","logic"]}
• Control: If, Switch, Case, fault for structured errors
• Functions: Map, Reduce, Filter, Distinct, Take, JoinText, Format, TicksToDate, point, and many more

A more elaborate example lives in FuncScript/TestFormula.text, where a payroll table is generated via mapping and HTML string templates.

Extending the Runtime

Custom functions are regular .NET classes implementing IFsFunction:

public class HexFunction : IFsFunction
{
    public string Symbol => "hex";
    public int MaxParsCount => 1;
    public CallType CallType => CallType.Prefix;
    public int Precedence => 0;

    public object Evaluate(IFsDataProvider context, IParameterList parameters)
    {
        var value = Convert.ToInt64(parameters.GetParameter(context, 0));
        return $"0x{value:X}";
    }

    public string ParName(int index) => "value";
}

Create a parameterless constructor, reference the assembly, and DefaultFsDataProvider.LoadFromAssembly(...) will auto-register the symbol (including optional aliases via FunctionAliasAttribute).

SQL & GIS Helpers

FuncScript.Sql adds converters for Sql* types and NetTopologySuite geometries plus GIS helpers such as point(x, y). Reference the project alongside the core library to normalize database values before exposing them to scripts.

JavaScript Port (Experimental)

The js-port/ folder contains a progressively feature-complete JavaScript interpreter that mirrors the .NET runtime. See js-port/AGENTS.md and js-port/port-progress.md for implementation notes and status.

Testing

Run the NUnit suite to ensure language changes remain backwards compatible:

dotnet test FuncScript.sln

Contributing

Issues and pull requests are welcome. If you plan substantial language or runtime changes, open an issue first so we can align on approach.

Maintainers

• Tewelde Ma. Tegegne (teweldemat@gmail.com)

License

Released under the MIT License. See LICENSE for details.