On 25-Mar-2003, Tom Pledger <Tom.Pledger@peace.com> wrote:
The floating point part of the GNU mp library looks difficult to fit into Haskell's numeric classes, because the type signatures in class Floating don't include a how-much-precision-do-you-want parameter.
How about using a function type which takes a precision and gives you back an answer to that many digits, and making this function type an instance of the numeric type classes? E.g. data MPF_T -- abstract, corresponds to GNU mp's mpf_t type PRECISION = Int type ARBITRARY_PRECISION_REAL = (PRECISION -> MPF_T) instance Floating ARBITRARY_PRECISION_REAL where sqrt x = (\prec -> mpf_sqrt_ui (x (prec + sqrt_lossage))) where sqrt_lossage = 1 -- amount of precision lost by sqrt ... Here mpf_sqrt_ui would be an interface to GMP's mpf_sqrt_ui() function, which takes as input an mpf_t and a precision and produces an mpf_t as output. -- Fergus Henderson <fjh@cs.mu.oz.au> | "I have always known that the pursuit The University of Melbourne | of excellence is a lethal habit" WWW: <http://www.cs.mu.oz.au/~fjh> | -- the last words of T. S. Garp.