A modern language for .NET

Write expressive programs.
Keep the whole platform.

Raven brings typed, expression-oriented programming, algebraic modeling, and familiar object-oriented design to the .NET ecosystem.

Learn Raven Try it online

Raven is under active development. Evolving areas are marked in the documentation.

Domain modeling · quote.rvn

record Shipment(Id: int, Weight: decimal)

union QuoteResult {
    case Quoted(amount: decimal)
    case Rejected(reason: string)
}

func Quote(shipment: Shipment) -> QuoteResult {
    if shipment.Weight <= 0 {
        return .Rejected("Weight must be positive")
    }

    return .Quoted(12.50m + shipment.Weight * 1.75m)
}

Records, unions, functions, and explicit statesLearn more

Web API · Program.rvn

import AspNetMinimalApi.Domain.*
import Microsoft.AspNetCore.Builder.*

let builder = WebApplication.CreateBuilder(args)
builder.Services.AddOpenApi()

use app = builder.Build()
app.MapGet("/", func () => GetApiInfo())
app.MapGet("/pets/{id}", FindPet)
app.MapGet("/pets", StreamPets)
app.MapPost("/pets/find", LookupPet)

app.Run()

ASP.NET Core, handlers, records, and unionsLearn more

Embedded IoT · temperature.rvn

union TemperatureState {
    case SensorUnavailable
    case Comfortable(celsius: double)
    case TooHot(celsius: double)
}

func ActOn(state: TemperatureState, alarm: GpioPin) {
    match state {
        .SensorUnavailable => alarm.Write(PinValue.High)
        .Comfortable(_) => alarm.Write(PinValue.Low)
        .TooHot(_) => alarm.Write(PinValue.High)
    }
}

.NET nanoFramework, sensor states, and GPIOLearn more

Blazor component macros · Greeting.rvn · experimental

import System.Console.*

component! Greeting(Name: string = "") {
    WriteLine("Rendering Greeting for ${Name}")

    markup! {
        <section class="greeting">
            <h1>Hello {Name}</h1>
        </section>
    }
}

Composable macros expressed through ordinary BlazorLearn more

Start here

One clear path into Raven.

Begin with the language itself. Install the compiler when you are ready to run a program locally.

1 Raven in 60 seconds
Read one small program and learn the ideas that shape the language.
2 Take the language tour
See functions, data modeling, patterns, failure handling, objects, and .NET interop.
3 Build and run Raven
Set up the source-built toolchain and create your first project.

Coming from .NET? Use the default path above, or keep the Raven for C# developers guide beside it.

A real .NET workload

Build an ASP.NET Core API.

The pet-shelter sample uses ordinary ASP.NET Core routing, OpenAPI, async handlers, and streaming responses. Raven records and unions model the API domain without giving up the framework you already know.

Build the web API

ASP.NET CoreMinimal APIs and dependency injection

Typed domainsRecords, unions, and pattern matching

Production shapesOpenAPI, async handlers, and streams

Already learning Raven? Go directly to the language feature guides, look up syntax and precise rules in the language reference, or open the tooling documentation.

Write expressive programs.Keep the whole platform.

One clear path into Raven.

Build an ASP.NET Core API.

Write expressive programs.
Keep the whole platform.