> The purpose of a type system is to prove something about the code The workaday purpose of these type systems is to write more of your intentions into the act

> The purpose of a type system is to prove something about the code The workaday purpose of these type systems is to write more of your intentions into the actual program code and get the compiler to enforce them on your behalf. That may seem like a mere restatement, but the shift in viewpoint can give tangible benefits to someone who is new to ML-style languages and isn't convinced that making the compiler happy is doing them more good than the pain it's causing them.