There is an atomic package in standard library.

What's wrong with it?

• Interfaces not uniform: if I change a type of a field from uint32 to uint64 I have to go and fix each and every bit of code that touches it.
• Not protecting me from accidentally accessing the atomic variable in a non-safe way.

This package provides a uniform, clean interfaces and type safety.

Bonus: Once which can happily replace sync.Once and it's close relative First.

Once used less memory (just 4 bytes, single uint32) and is lock free.

Benchmarks (on MacBook Pro circa mid 2014):

name        time/op
SyncOnce-8  2.12ns ± 3%
Once-8      2.01ns ± 4%
First-8     1.93ns ± 2%

Docs are here.