Just looked at the matlab code... It doesn't in general do too much overloading - the only obvious example I can find is with matrix multiplication '*'. Here it multiplies matrices normally unless either of the arguments is a scalar, in which case the scalar is multipled by each element of the other matrix. The other multiply operator '.*' multiplies each element in one matix by the same element in the other matrix (as in addition, so matrices must be the same sizes)... If I were going to implement everything in Haskell I would probably use a data type like: data Matrix a e = Matrix [Int] (a Int e) type UMatrix e = Matrix UArray e Where [Int] is a list of dimensions, ie for a scalar [ ], a vector [3], 2D matrix [3,4], or a higher dimensional matrix [3,4,5,6]. It is possible to get static typing using type level naturals... something like: data Matrix d a e = Matrix d (a Int e) The use an HList (or equivalent) to encode the dimensionality of the matrix in the type. For example define [D0 x .. D9 x, DNil] as decimal type constructors, you would then get: type Matrix2x3 a e = Matrix (HCons (D2 DNil) (HCons (D3 DNil) HNil)) a Int e However as the built in operators +,-,*,/ etc have the type "a -> a -> a" you could not define '*' to mean matrix multiplication. At the moment I favour using dynamic size checking on the matrices, and overloading all the standard Haskell Numeric operators for matrices. I seems easier to use FFI and LAPACK for the more complex matrix operations... anyone know how to marshall data for Fortran? Keean. Bulat Ziganshin wrote:
Hello Keean,
Thursday, June 09, 2005, 8:52:55 PM, you wrote:
KS> (sometimes the best is the enemy of the good!)
i think that best in this case will be splitting library to "low-level" and "high-level" parts, where low-level part implements functions like "miltipleMatrixByScalar", "miltipleMatrixByMatrix" and so on and high-level part implements matlab-like or strong-typed access to this functions via appropriate overloaded operators and so on. so in this case low-level==semantics and high-level==syntax
moreover, low-level interface must be general enough to allow different implementations - haskell, template haskell, ffi->lipack