Your first app

Create a module

mkdir hello && cd hello
go mod init example.com/hello

Write the app

Save this as main.go:

// The first app: a label and a button that changes it.
package main

import (
	"github.com/belluikit/bellui"
	"github.com/belluikit/bellui/app"
	"github.com/belluikit/bellui/container"
	"github.com/belluikit/bellui/widget"
)

func main() {
	a := app.New()
	w := a.NewWindow("Hello")

	hello := widget.NewLabel("Hello Bellui!")
	w.SetContent(container.NewVBox(
		hello,
		widget.NewButton("Hi!", func() {
			hello.SetText("Welcome :)")
		}),
	))

	bellui.ShowAndRun(w)
}

Reading it from the top:

• app.New() creates the application. There is one per program.
• a.NewWindow("Hello") creates a window. Nothing is shown yet.
• widget.NewLabel and widget.NewButton create two widgets. The button’s function runs on the UI thread each time it is tapped, so it can update the label directly.
• container.NewVBox stacks them vertically, and w.SetContent makes the stack the window’s content.
• bellui.ShowAndRun(w) shows the window and runs the app’s event loop. It returns when the app quits, for example when you close the window. It is a function in the bellui package that takes the window, not a method on it.

Fetch the dependencies

go mod tidy

Run this after writing the code, not before. go mod tidy adds exactly the modules your imports need, and on an empty module it has nothing to go on.

Run it

go run .

A window opens with the label and the button. Tap the button and the label changes.