Jacek Generowicz wrote:
# Imagine an activity which may be performed either by a computer, or
# by a human (alternatively, either locally, or remotely across a
# network). From Haskell's type system's perspective, these two will
# look completely different (most obviously, the human (or the
# network) is wrapped in IO). How can they be made interchangeable ?
# To demonstrate what I mean, I offer the following concrete toy
# example, in Python.
# It's a harness for playing the trivial higher-lower number guessing
# game, with interchangeable strategies for either player. In this
# example I provide two strategies (Computer / ask Human via IO) for
# each role (asker and guesser).
# How can this sort of interchangeability of computations which are
# conceptually identical, but incompatible from the types perspective,
# be expressed in Haskell?
Have a look at my operational package, in particular the TicTacToe.hs
example on the examples page.
http://hackage.haskell.org/package/operational
(Unfortunately, the haskell.org domain is seized at the moment, so
this link won't work for a while. Also, please yell if you can't find
the examples page once the link works again.)
Regards,
Heinrich Apfelmus
--
http://apfelmus.nfshost.com
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