How to know if a variable of arbitrary type is Zero in Golang?

Question

Because not all types are comparable, e.g. a slice. So we can't do this

var v ArbitraryType
v == reflect.Zero(reflect.TypeOf(v)).Interface()

Answer 1

Go 1.13 introduced Value.IsZero method in reflect package. This is how you can check for zero value using it:

if reflect.ValueOf(v).IsZero() {
    // v is zero, do something
}

Apart from basic types, it also works for Chan, Func, Array, Interface, Map, Ptr, Slice, UnsafePointer, and Struct.