[chriswarbo]

> tests shouldn't be needed, at least in theory

Tests are very useful for distinguishing between "what a function does" and "what you think a function does". Especially when you're building on functions written by others. Types and documentation help too, but if someone's already misunderstood something, such descriptive information might still fit nicely with their incorrect world view.

Personally, I can't live without QuickCheck :)