The most important part in here by SPJ is "haskell is a playground for language design" and by John that "haskell's strength is playing with DSLs". Haskell started and is a research language; that is PRO and not a con. It gives simon the ability to give a talk at POPL saying look at this cool dependently-typed feature, and btw, the compiler you just downloaded already compiles these programs. We need more languages that are bridging the gap between cutting edge research and production compilers.
I somehow got the feeling that, working for Microsoft, SPJ couldn't say "Haskell is the language for everything", even if he wanted to, because that would undermine the official position of his employer.
But then, maybe he could say it. I don't know.
haha that what they should answer at the clever flipped question. Haskell is the answer for all the questions, in originality order.
I would like to hear the "silly question" referenced at 10:55 but can't seem to find a link to Simon Peyton-Jones's keynote.