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A type switch lets you execute different code depending on the concrete type stored inside an interface value at runtime.

Syntax: `switch v := i.(type) { … }`

• Handle multiple possible concrete types in one function.
• Safely branch logic without multiple chained type assertions.
• Implement polymorphic behavior for `any` / `interface{}` inputs.

package main
 
import "fmt"
 
func handle(i any) {
    switch v := i.(type) {
    case int:
        fmt.Println("int:", v+1)
    case string:
        fmt.Println("string:", v+"!")
    default:
        fmt.Println("unknown type")
    }
}
 
func main() {
    handle(10)
    handle("go")
    handle(true)
}

• A type switch works only on interface values (including `any`).
• The variable `v` inside each case has the concrete type for that case.
• Use type switches sparingly—prefer interfaces with methods when possible.

• Interface
• Type assertion
• Type switch
• any / interface{}

• type switch /taɪp swɪtʃ/: switch theo kiểu
• concrete type /ˈkɑːnkriːt taɪp/: kiểu thật bên trong interface
• interface /ˈɪntərfeɪs/: giao diện
• runtime /ˈrʌntaɪm/: lúc chương trình đang chạy
• polymorphic /ˌpɑːlɪˈmɔːrfɪk/: đa hình
• sparingly /ˈsperɪŋli/: dùng hạn chế