[oct]

Just because Haskell is purer that doesn't mean ML is pointless. Under the right circumstances even a functional program can benefit from mutable state. One example (perhaps the only real example; I don't know) can be found in the SML New Jersey implemetation of splay trees, which modifies the tree during certain operations.

Even without the purity question there are other things to consider. ML is evaluated strictly, for example. I don't know much Haskell but I don't believe it has any direct counterpart to ML's functors, either. There are probably many other differences. Haskell is definitely more popular and is still a niche language, so the reason you don't hear much about ML's benefits is probably just because it has so few users.

[redo2]

Thanks.