How to maintain a set of integer sequences?

To construct a set, we can use a map:

set := make(map[string]bool)
set["Foo"] = true
foo_exists := set["Foo"]

What if we want a set of integer sequences? Go compiler complains Invalid key type []int for make(map[[]int]bool).

Set is a commonly used basic data type that has a lot of uses. For example, a set of integer sequences can be used in a password generating/cracking program to record passwords that have been generated/tried. This enables the program to quickly look up generated/tried passwords to avoid generating/trying them again. This data structure is simply so basic that it should be expected to be used from time to time within various kinds of applications.

As explained in @Wishwa Perera's answer, types which are not comparable are can not use as map key. So you can encode, or convert different type to your int slices and then insert to the map.

In below example, I convert int slice to string and insert to the map. But this is not good for long int slices because string is become more longer and more time consumed to run the code.

You can use hashing to solve that problem.

package main

import (
	"fmt"
)

type intArray []int

func (i intArray) toString() string{
	return fmt.Sprintf(`%+v`, i)
}

func main()  {
	myMap := make(map[string]bool)
	arr1 := []int{1, 2, 3, 4}
	myMap[intArray(arr1).toString()] = true

	arr2 := []int{1, 2, 3, 4}
	arr2Exist := myMap[intArray(arr2).toString()]
	fmt.Println(`is array 2 exist : `,arr2Exist) //is array 2 exist :  true

	arr3 := []int{1, 2, 3, 4, 5}
	arr3Exist := myMap[intArray(arr3).toString()]
	fmt.Println(`is array 3 exist : `,arr3Exist) //is array 3 exist :  false
}

You can run here

The map key can be any type that is comparable. Some of them are:

• Boolean
• Numeric
• String
• Pointer
• Channel
• Interface types
• Structs — if all it’s field type is comparable
• Array – if the type of value of array element is comparable

Some types which are not comparable and which cannot be used as a key in a map are:

• Slice
• Map
• Function

What you have used is a slice,use an array instead, define a size (let say 5) as make(map[[5]int]bool) and it will compile.