I started using Go back around 2015 and was immediately surprised by the lack of any type of generic type system. Sure, the empty interface{} existed, but that was hardly the same. At first I thought I wanted needed generics in Go, but over time I began appreciating the simplicity of the language. So when I learned of discusisons to introduce generics in Go 2.0, I was ambivalent at best. Once the timetable to introduce generics was accelerated to Go 1.18, I decided it was time to take a closer look at the proposal.

After spending some time playing with them, I began to appreciate how generics in Go have been designed and implemented with the same elegance and simplicity as Go itself. I hope you will agree, and to that end, this repository is a hands-on approach to learning all about generics in Go.

• Labs: a hands-on approach to learning Go generics
• FAQ: answers to some of the most frequently asked questions regarding Go generics
• Links: links to related reference material and projects that use generics

1. Prerequisites: how to install the prerequisites required to run the examples in this repository
2. Hello world: a simple example using generics
3. Getting started: an introduction to go generics
4. Getting going: basic concepts explored
5. Internals: how generics are implemented in golang
6. Benchmarks: basic benchmarks for common patterns using generics

• How are you using generics in the Go playground?
• What is T?
• What is this any I keep seeing everywhere?
• What does the tilde ~ do?
• Do Go generics use type erasure?

While it is true that the Go playground uses the most recent, stable release of Go, there is also a Go playground that uses the tip at https://gotipplay.golang.org, and this playground supports generics.

The symbol T is often used when discussing generic types because T is the first letter of the word type. That is really all there is too it. Just like x or i are often the go-to variable names for loops, T is the go-to symbol for generic types.

For what is worth, K is often used when there is more than one generic type, ex. T, K.

The word any is a new, predeclared identifier and is equivalent to the empty interface in all ways. Simply put, writing and reading any is just more user friendly than interface{} 😃.

The ~ symbol is used to express that T may be satisfied by a concrete type directly, by implementation, or via type alias. To learn more about type constraints and the ~ symbol, please refer to the section Tilde ~.

Generics in Go are not implemented with type erasure. Please jump to Internals for more information.

• Type parameter proposal: the accepted proposal for introdicing generics to go
• Getting started with generics: a tutorial from the authors of go for getting started with generics

• Controller-runtime: a write-up and patchset for implementing conditions logic, patch helpers, and simple reconcilers using generics