> (and to be fair, free theorems are only interesting when polymorphism is involved which I definitely didn’t want to go into). "there's a thing called polymo

> (and to be fair, free theorems are only interesting when polymorphism is involved which I definitely didn’t want to go into). "there's a thing called polymorphism, and it means 'of many forms', what it means is that if you put the thing in, you're guaranteed to get a specific type of thing out, but it might be different depending on what you put in. So you put words into the machine, and letters come out, but if you put lists of numbers in, numbers come out."