Nim (1.4 ORC) v.s. Rust in terms of safety?

[snej]

I've put my money where my mouth is and written [an 
RFC](https://github.com/nim-lang/RFCs/issues/302) ... not for `unsafe` itself, 
but for two extensions to the effects system that would allow it to be 
partially implemented in Nim code. I think these extensions would have other 
uses as well, and I give an example involving database transactions. Hopefully 
even those who disagree with `unsafe` will find this useful.