> What I meant was that the space the program will use isn't defined by the language itself and can't be known at compile time. You can know the space usage (i

> What I meant was that the space the program will use isn't defined by the language itself and can't be known at compile time. You can know the space usage (in relation to input size) of some Haskell programs at compile-time — e.g. if you use a constant-memory streaming abstraction. I don’t know much about Rust, but I don’t think it guarantees known space usage of all possible programs at compile-time.