On Wed, Mar 16, 2011 at 7:52 AM, Andrew Coppin <andrewcop...@btinternet.com> wrote: >>> Hmm, yes. That will work, but I wonder if there's some way of doing this >>> that doesn't limit the scope of the container to one single span of >>> code... >> >> You can write helper functions which take containers as argument by >> parameterizing these helper functions over s: >> >> takesTwoContainers :: Container s1 -> Container s2 -> ... >> takesTwoContainers c1 c2 = ... -- c1 and c2 can be used here >> >> This function could be called like this: >> >> withContainer (\c1 -> >> withContainer (\c2 -> >> takesTwoContainers c1 c2)) -- c1 and c2 can be used here >> >> In this example, the scope of the containers is not limited to a single >> span of code. > > What you can't do is write functions such as > > foo :: Container x -> (Cursor x, Cursor x) > > for example.
I don't follow. foo = cursor &&& cursor Did you mean to have some extra condition on foo that can't be satisfied? Luke _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
