I wrote http://manishearth.github.io/blog/2015/05/27/wrapper-types-in-rust-choosing-your-guarantees/ http://manishearth.github.io/blog/2015/05/27/wrapper-types-

I wrote http://manishearth.github.io/blog/2015/05/27/wrapper-types-in-rust-choosing-your-guarantees/ http://manishearth.github.io/blog/2015/05/27/wrapper-types-i... which explains the primitives that can be composed together to do things like this.