Trying GHCJS

Output

$ ghcjs -O2 test.hs
[1 of 1] Compiling Main             ( test.hs, test.js_o )
Linking test.jsexe (Main)
$ (cd test.jsexe/ && node all.js)
(0,1)
(1,2)
(2,4)
(3,8)
(4,16)
(5,32)
(6,64)
(7,128)
(8,256)
(9,512)
(10,1024)
(11,2048)
(12,4096)
(13,8192)
(14,16384)
(15,32768)
(16,65536)
(17,131072)
(18,262144)
(19,524288)
(20,1048576)
(21,2097152)
(22,4194304)
(23,8388608)
(24,16777216)
(25,33554432)
(26,67108864)
(27,134217728)
(28,268435456)
(29,536870912)
(30,1073741824)
(31,-2147483648)
(32,0)
(33,0)
(34,0)
(35,0)
(36,0)
(37,0)
(38,0)
(39,0)

test.hs

module Main where

import Data.List (unfoldr)
import Control.Monad (mapM_)

type I = Int

step :: (Int,I) -> Maybe ((Int,I), (Int,I))
step (i,x) = Just ((i,x), (1+i,2*x))

main :: IO ()
main = mapM_ print $ take 40 (unfoldr step (0,1))