Hi folks, My primary language is R, which is an imperative functional language. I start to learn haskell and try to use it instead when a project is time-consuming and it takes months in R. I like the language very much so far, but I do miss some important functions in R which can generate random numbers from all kinds of distributions. R provides a standalone library in c which contains all these functions and I try to write a wrapper for haskell. Since I am very new to haskell, I want to hear some suggestions to confirm that I am on the right track. The functions are the following: void set_seed(unsigned int, unsigned int); void get_seed(unsigned int *, unsigned int *); they can set or get seed for random number generator. For any distribution, we have four functions for it -- Normal distribution double dnorm4(double x, double mu, double sigma, int give_log) double pnorm5(double x, double mu, double sigma, int lower_tail,int log_p) double qnorm5(double p, double mu, double sigma, int lower_tail, int log_p) double rnorm(double mu, double sigma) where dnorm calculates density, pnorm calculates p-value, qnorm calculates quantile, and rnorm generates normal random variables. dnorm, pnorm, qnorm are easy since they don't have side-effect. I think I can just use the following: foreign import ccall "dnorm4" dnorm :: Double -> Double -> Double-> Int -> Double foreign import ccall "pnorm5" pnorm :: Double -> Double -> Double-> Int -> Int -> Double foreign import ccall "qnorm5" qnorm :: Double -> Double -> Double-> Int -> Int -> Double (Should I use CDouble or CInt here?) But for rnorm, if I use "foreign import ccall rnorm :: Double -> Double -> IO Double", then my main function should carry IO monad all the time. Maybe the better way is that I should "encapsulate" it into a state monad rng -> (rng, randomnumber). Therefore for rnorm, I should first write a wrapper in c like seed2 rnorm_wrapper(seed1, parameters){ set_seed(seed1); rnorm(parameters); get_seed(seed2); } and then write another wrapper for rnorm_wrapper in haskell. Can somebody tell me if this is the right approach? Thank you! Best, Peng