On Thu, 30 Jun 2005, Jacques Carette wrote: > Henning Thielemann wrote: > > >I'm uncertain about how who want to put the different kinds of > >multiplication into one method, even with multi-parameter type classes. > >You need instances > > > > (*) :: Matrix -> Matrix -> Matrix > > (*) :: RowVector -> Matrix -> RowVector > > > > > [many other instances removed.] > > Definitely not. You could do: > Data Orientation = Row | Column > Data Vector a = Vector Orientation [a]
In the first mail you wrote "9. There are row vectors and column vectors, and these are different types. You get type errors if you mix them incorrectly." I interpreted that you want to encode the information Row or Column into the type. This sounds reasonable to me because multiplying e.g. a column vector by a matrix is so obviously wrong that it should be detected statically. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
