Simon Peyton Jones

OCaml's gained lots of fancy type systems.

Some of them, Haskell and OCaml have learned from each other.

OCaml has got an interesting effect system recently and a whole lot of new extensions.

It's an absolute hotbed of innovation at the moment, OCaml.

So I view OCaml and Haskell as kind of siblings.

Brothers and sisters, right?

We love each other.

We learn from each other.

We compete with each other.

All of the things that siblings do.

But they're not the same, right?

So siblings don't say, I'm just better than you.

You shouldn't exist.

We say, let's enjoy our life together.

Why is laziness good?

John Hughes did this rather well way ago, 1980-something.

He wrote a program called Why Functional Programming Matters.

And one of its main theses was that lazy evaluation lets you compose programs in a particularly modular way.

So imagine a program that is, I mean, his classic example is a program that plays chess, right?

So one thing you could do is you could imagine building a tree of all possible moves starting from the position we're at.