Simon Peyton Jones

At least it lets you apply a function to a string and get back another string.

So, of course, we then worked on how could we do IO in Haskell in a safe way?

And that will lead to, you know, monads and stuff.

So just as we're moving from C horizontally to go safer and safer, but staying useful.

So from Haskell, we're moving sort of vertically to get more and more useful without stopping being safe.

And Nirvana is when we sort of meet up, right?

But the point is not to say one is better than the other, but just to say that we both seek things that are useful and safe.

So when you say F applied to 3 plus 4, it'll add 3 plus 4 and then call F to get 7 right.

In our school, if you say F of 3 plus 4, it'll build a little suspension that says, well, if you ever need this 3 plus 4, you can evaluate it, but maybe you'll never need it.

And then it calls F. That's a lazy language.

So because OCaml is strict, it has a defined order of evaluation.

So if you say f of 3 plus 4 and a second parameter 8 plus 9, it'll evaluate 3 plus 4 and then 8 plus 9 in that order.

So it makes sense to say you can say f of print hello, print goodbye.

Because you get hello and then goodbye printed.

So once you have a defined order of evaluation, then it's pretty easy to incorporate I.O.

Even though it quotes a functional language,

OCaml allows you to do I.O.

without saying unsafe perform I.O.

or anything.

In fact, it has a defined order of evaluation and it's perfectly kosher to do that.