Any difference in using an empty interface or an empty struct as a map's value?

I am using this construct to simulate a set

type MyType uint8
map[MyType]interface{}

I then add in all my keys and map them to nil.

I've learnt that it is also possible to use

map[MyType]struct{}

Any benefits of using the empty struct versus interface{}.

Memory usage. For example, types struct{}, interface{}, and bool,

package main

import (
	"fmt"
	"unsafe"
)

func main() {
	var s struct{}
	fmt.Println(unsafe.Sizeof(s))
	var i interface{}
	fmt.Println(unsafe.Sizeof(i))
	var b bool
	fmt.Println(unsafe.Sizeof(b))
}

Output (bytes for 32-bit architecture):

0
8
1

Output (bytes for 64-bit architecture):

0
16
1

References:

Go Data Structures: Interfaces

The empty struct and empty interface, though syntactically similar, are actually opposites. An empty struct holds no data; an empty interface can hold any type of value. If I see a map[MyType]struct{}, I know immediately that no values will be stored, only keys. If I see a map[MyType]interface{}, my first impression will be that it is a heterogenous collection of values. Even if I see code storing nil in it, I won't know for sure that some other piece of code doesn't store something else in it.

In other words, using struct{} makes your code much more readable. It also saves a little memory, as described in the other answer, but that is just a fringe benefit of using the right tool for the job.

I would like to add additional detail about empty struct , as differences are already covered by andybalholm and peterSO .

Below is the example which shows usability of empty struct .

> Creates an instance of rectangle struct by using a pointer address
> operator is denoted by & symbol.

package main

import "fmt"

type rectangle struct {
	length  int
	breadth int
	color   string
}

func main() {
	var rect1 = &rectangle{10, 20, "Green"} // Can't skip any value
	fmt.Println(rect1)

	var rect2 = &rectangle{}
	rect2.length = 10
	rect2.color = "Red"
	fmt.Println(rect2) // breadth skipped

	var rect3 = &rectangle{}
	(*rect3).breadth = 10
	(*rect3).color = "Blue"
	fmt.Println(rect3) // length skipped
}

Reference : https://www.golangprograms.com/go-language/struct.html

For a thorough read you can refer : https://dave.cheney.net/2014/03/25/the-empty-struct