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.