Go 1.21 Release Candidate - eviltoast
Go 1.21 Release Candidate - The Go Programming Language
go.dev
Go 1.21 RC brings language improvements, new standard library packages, PGO GA, backward and forward compatibility in the toolchain and faster builds.

Go 1.21 RC released today. Some really interesting new additions. I’m pretty excited to see the map and slice package additions that contain a lot of generic methods. Will be nice not to have to maintain my own going forward.