This is a very basic implementation of a set collection type in golang

http://en.wikipedia.org/wiki/Set_(computer_science)

"In computer science, a set is an abstract data structure that can store certain values, without any particular order, and no repeated values. It is a computer implementation of the mathematical concept of a finite set. Unlike most other collection types, rather than retrieving a specific element from a set, one typically tests a value for membership in a set."

This implementation supports initializing empty sets and sets with an initial collection. It supports adding and removing items. You can test whether a set contains a specific value, whether the set is empty, or whether the set is a subset of another set. You can check for the set size, pop items from the set, clear the content of the set, and return an enumerator of the set contents. You can map a function against the set contents and filter a set against a filter function. Additionally, you can get the union, intersection and difference of two sets.

package main

import(
    "github.com/shopsmart/set"
    "log"
)

func main() {
    // Initialize an empty set
    mySet := set.New()

    // Initialize a set with a collection of values
    colors := set.New("red", "blue", "green", "yellow")

    // Add items
    colors.Add("purple")

    // Check to see if an item is in the set
    log.Println(colors.Contains("red")) // true

    // Check the size of the set
    log.Println(colors.Size()) // 5

    // Distinct values will only be added one time
    colors.Add("purple")
    log.Println(colors.Size()) // Still 5

    // Check to see if a set is empty
    log.Println(mySet.IsEmpty()) // true
    log.Println(mySet.Size()) // 0
    log.Println(colors.IsEmpty()) // false
    log.Println(colors.Size()) // 5

    // Remove items from the set
    colors.Remove("red")
    log.Println(colors.Contains("red")) // false

    // Clear a map
    colors.Clear()
    log.Println(colors.IsEmpty()) // true
    log.Println(colors.Size()) // 0
}