Simon Peyton Jones talks about the right measure of success and hence freedom a programing language should have to evolve without the chains of backward compatibility.

As for the second, I don’t know if you know this, but Haskell has a sort of unofficial slogan: avoid success at all costs. I think I mentioned this at a talk I gave about Haskell a few years back and it’s become sort of a little saying. When you become too well known, or too widely used and too successful (and certainly being adopted by Microsoft means such a thing), suddenly you can’t change anything anymore. You get caught and spend ages talking about things that have nothing to do with the research side of things.

Simon works in the design and implementation of the GHC, which is a state-of-the-art, open source, compiler and interactive environment for the functional language Haskell.