Quickstart: Hello, G#
This page builds the smallest checked-in G# program two ways: with an SDK project and with gsc directly.
The program
samples/HelloWorld.gs contains:
// file: HelloWorld.gs
package HelloWorld
import System
Console.WriteLine("Hello, world!")
Expected output:
Hello, world!
The first non-comment line declares the package. Packages give code a namespace-like identity for compilation and imports. import System brings the CLR System namespace into scope, so the program can call Console.WriteLine. The last line is a top-level statement: G# can synthesize the executable entry point for simple programs without requiring an explicit func Main.
Run it with the SDK
Create a console project, replace its Program.gs with the program above, then build and run:
dotnet new install Gsharp.Templates
dotnet new gsharp-console -n HelloWorld
cd HelloWorld
dotnet build
dotnet run
The SDK path is the everyday workflow. Gsharp.NET.Sdk wires .gs files into MSBuild, passes project references and target framework information to gsc, and emits a normal .NET executable.
Run it with gsc directly
When you pass source files to gsc without /out, the compiler emits the program and runs it immediately:
dotnet path/to/gsc.dll samples/HelloWorld.gs
Output:
Hello, world!
Success.
The Success. line is printed by gsc after the emitted program completes.
To save the emitted assembly, add /out. For an executable, keep /target:exe; /tfm selects the target framework runtime config.
dotnet path/to/gsc.dll samples/HelloWorld.gs /out:artifacts/HelloWorld.dll /target:exe /tfm:net10.0
dotnet artifacts/HelloWorld.dll
Output:
Hello, world!
Both direct commands use the compiler emitter. Omit /out for immediate execution; add it when you need a reusable assembly.
Next: A Tour of G#.