6 ms·

That's indeed nice, and made me change my mind somewhat. I wonder if you can write a napkin example that mixes ST with randomness, instead of using IO for every

• tome 9y ago
  It's not too bad to manually thread a seed around. import qualified Data.Vector.Mutable as V import Control.Monad (when) import qualified System.Random as R import Control.Monad.ST st = runST $ do v <- V.replicate 10 0 setIncreasing v addRandomness v printThemAll v = loop 0 (V.length v) where loop i n = do when (i < n) $ do e <- V.read v i print e loop (i + 1) n setIncreasing v = loop 0 (V.length v) where loop i n = do when (i < n) $ do V.write v i (i * 2) loop (i + 1) n addRandomness v = loop initial_g 0 (V.length v) where seed = 1234 initial_g = R.mkStdGen 1234 -- Seed loop g i n = do when (i < n) $ do let (r, next_g) = R.random g e <- V.read v i V.write v i (e + r) loop next_g (i + 1) n
  • cousin_it 9y ago
    I see, thanks! The imperative version would still look more direct to me, but your versions are very nice.