I first heard this phrase applied to Haskell. Both Haskell and Rust have sophisticated type systems, Haskell more-so than Rust. With a sophisticated type system

I first heard this phrase applied to Haskell. Both Haskell and Rust have sophisticated type systems, Haskell more-so than Rust. With a sophisticated type system, you can accurately encode the rules of your domain in the types and thus, when the program compiles you can be confident it will do the right thing. Having written a fair amount in both languages as well as many others I find this to hold true. The phrase isn't, primarily anyway, about Rust's memory safety guarantees in my mind.