Interfaces in Go
From the Go cheat sheet · Interfaces · verified Jul 2026
Interfaces
Defining and implementing interfaces
go
// Define interface
type Shape interface {
Area() float64
Perimeter() float64
}
// Implement interface
type Rectangle struct {
Width, Height float64
}
func (r Rectangle) Area() float64 {
return r.Width * r.Height
}🎯 Implicit interface implementation
📦 interface{} for any type
🔄 Type assertions and type switches
⚡ Small interfaces are better (Interface Segregation)