trjhtr

I'm trying to return unique items in a Go slice. I've landed on the following, but it seems rather sub-optimal. I'm new to golang (first project in it) and wondering if there's a better way to approach this?

// 
// Returns unique items in a slice
//
func Unique(strSlice string) string 
 keys := make(map[string]bool)
 list := string 
 for _, entry := range strSlice 
 if _, value := keys[entry]; !value 
 keys[entry] = true
 list = append(list, entry)
 
 
 return list

This is not idiomatic writing style in Go, because the value variable is misleading:

if _, value := keys[entry]; !value {

The first returned value is the value in the map, the second value indicates success or failure of the lookup.
So rename it to ok or found.

If the slice is very large,
then list = append(list, entry) may lead to repeated allocations.
In that case, you can optimize by preallocating list to the maximum possible capacity (len(strSlice)), and assign elements by index rather than using append.
But if you have no reason for this optimization then don't do it,
that would be premature optimization,
the current solution is fine.

Instead of creating you final slice during the loop, you could do two loops: one for creating the map and another to turn it into a slice:

//
// Returns unique items in a slice
//
func Unique(slice string) string 
 // create a map with all the values as key
 uniqMap := make(map[string]struct)
 for _, v := range slice 
 uniqMap[v] = struct
 

 // turn the map keys into a slice
 uniqSlice := make(string, 0, len(uniqMap))
 for v := range uniqMap 
 uniqSlice = append(uniqSlice, v)
 
 return uniqSlice

If your are not interested into the value of the map, it is customary to store the empty struct.