The point is that you reach an area where the mathematical ideas don't map perfectly to the underlying functionality you're providing.
You can make your language "unsound" by violating those mathematical principles, or you can make something like the I/O monad. It is indeed "soundness" vs "practicality".
EDIT: Oh, and that link seems to have misunderstood the 'worse is better' philosophy -- C++ isn't the champion of 'worse is better', C is.
You can make your language "unsound" by violating those mathematical principles, or you can make something like the I/O monad. It is indeed "soundness" vs "practicality".
EDIT: Oh, and that link seems to have misunderstood the 'worse is better' philosophy -- C++ isn't the champion of 'worse is better', C is.