gibbs.hs

-- Run me with runhaskell gibbs.hs
-- Compile me with ghc gibbs.hs -main-is Gibbs

module Gibbs where

import Prelude hiding (putStrLn)
import qualified Data.ByteString.Lazy.Char8 as B

import qualified Data.Aeson as Aeson (encode)
import Data.Random (sampleFrom, RVar)
import qualified Data.Random.Distribution.Normal as N (doubleStdNormal, normal)
import Data.Vector (singleton)
import System.Random.MWC as MWC (initialize)

stdNormal = N.doubleStdNormal
normal :: Double -> Double -> RVar Double
normal = N.normal

rollM :: Monad m => Int -> (a -> m a) -> a -> m [a]
rollM 0 f initial = return []
rollM n f initial = do
        x <- f initial
        xs <- rollM (n - 1) f x
        return $ initial : xs

genPref = rollM 100 (\x -> normal x 0.007) 0.49

main = do
        mwc <- MWC.initialize (singleton 14)
        pref <- sampleFrom mwc genPref
        B.putStrLn $ Aeson.encode pref

gibbs.R

source("runhaskell.R")
plot(runhaskellJ("Gibbs.main"), type="l")

runhaskell.R

library(stringr)
runhaskell <- function(name) {
	module <- unlist(str_split(name, "\\.", n=2))[1]
	return(system(paste("export LD_LIBRARY_PATH=/usr/local/lib && echo 'import qualified ", module, "; main = ", name, "' | runhaskell"), intern=TRUE))
}
library(jsonlite)
library(functional)
runhaskellJ <- Compose(runhaskell, fromJSON)