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---
title: "Go's unique pkg"
tags: posts
toc: true
---
https://pkg.go.dev/unique
>The unique package provides facilities for canonicalising ("interning") comparable values.[^1]
[^1]: https://pkg.go.dev/unique
oh yeah, thats obvious I fully understand what this package does now, great read, tune in for the next post.
Interning, is the re-use of an object of equal value instead of creating a new one. I'm pretending I knew this but really I've just reworded [Interning](https://en.wikipedia.org/wiki/Interning_(computer_science)).
So lets try again.
If you're parsing out a csv of bank transactions, its very likely a lot of names will be repeated. Instead of allocating memory for each string representing a merchant, you can simply reuse the the same string.
So the dumbed down version might look like
```go
var internedStrings sync.Map
func Intern(s string) string {
if val, ok := internedStrings.Load(s); ok {
return val.(string)
}
internedStrings.Store(s, s)
return s
}
```
With a small demo here https://go.dev/play/p/piSYjCHIcLr
This implementation is fairly naive, it can only grow and it only works with strings, so naturally go's implementation is a better.
It's also worth noting, that since strings are a pointer under the hood
>When comparing two strings, if the pointers are not equal, then we must compare their contents to determine equality. But if we know that two strings are canonicalized, then it _is_ sufficient to just check their pointers.[^2]
[^2]: https://go.dev/blog/unique
So to recap, goes `unique` package provides a way to reuse objects instead of creating new ones, if we consider the objects of equal value.
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