Thanks for the patch, Don. I'm on vacation now, but I'll apply it when I get back. As for why "getDot" involves pattern matching, it is because a vector is either a pointer to raw storage, or a conjugated vector. I wrote a blog post about this for those of you who are interested ( http://quantile95.com/2008/06/12/blas-data-types/ ). The current data type is this: data DVector t n e = DV { fptr :: !(ForeignPtr e) , offset :: !Int , len :: !Int , stride :: !Int } | C !(DVector t n e) Now, it isn't strictly necessary to use an algebraic data type-- I could have just used a boolean flag, but the code is a little cleaner this way. I haven't done any tests to see what the difference in performance is. I would expect that a pattern match between two alternatives would be just as fast as checking a boolean flag. The good news is that this is a constant-time overhead. For larger vectors, getDot should approach the performance of a raw cblas_ddot call. Patrick