> Does 'the language prevents errors at compile time' really mean 'better function signatures in the standard library'? Because that's all I'm getting out of th

> Does 'the language prevents errors at compile time' really mean 'better function signatures in the standard library'? Because that's all I'm getting out of the regex example given. Of course any function can be forced to crash by inserting some crash-inducing code into the function. You can always make a function that assumes that value is of a certain form, and crashes the program if it is not (like unwrap for extracting a value from an Option, or crashing if it there is no value). In order to have "code that works if it compiles" (comparatively speaking; often used as an exaggeration), you have to have the discipline to use the facilities that the language provides you. I guess a language would need some kind of totality checker in order to make sure that you couldn't make function diverge in some way. Like for example Idris has. Rust also has the `!` type, aka bottom, for marking functions that diverge. > So far as I know the fail! macro still exists in Rust. What should that do? Crash the program? If so it should have been renamed to something like `panic!` now, since "fail" now is associated with Error types, while "panic" is associated with crashing the program/exceptions.