[Haskell-cafe] The difficulty of designing a sequence class

[ajb at spamcop.net]

G'day all.

Quoting David Menendez <zednenem at psualum.com>:

> That's a tough call to make. Changing the kind of Sequence to * from *
> -> * means losing the Functor, Monad, and MonadPlus superclasses and all
> the various maps and zips.

And on the other hand, containers that need extra constraints (e.g.
sets, which need their members to be Eq at the very least) can't be
Functors or Monads anyway.

Perhaps Functor/Monad/etc are the culprits here.

Cheers,
Andrew Bromage