diff options
Diffstat (limited to 'users/glittershark/xanthous/src/Xanthous/Random.hs')
-rw-r--r-- | users/glittershark/xanthous/src/Xanthous/Random.hs | 118 |
1 files changed, 0 insertions, 118 deletions
diff --git a/users/glittershark/xanthous/src/Xanthous/Random.hs b/users/glittershark/xanthous/src/Xanthous/Random.hs deleted file mode 100644 index 6d34109df7f8..000000000000 --- a/users/glittershark/xanthous/src/Xanthous/Random.hs +++ /dev/null @@ -1,118 +0,0 @@ --------------------------------------------------------------------------------- -{-# LANGUAGE UndecidableInstances #-} -{-# OPTIONS_GHC -fno-warn-orphans #-} --------------------------------------------------------------------------------- -module Xanthous.Random - ( Choose(..) - , ChooseElement(..) - , Weighted(..) - , evenlyWeighted - , weightedBy - , subRand - , chance - , chooseSubset - ) where --------------------------------------------------------------------------------- -import Xanthous.Prelude --------------------------------------------------------------------------------- -import Data.List.NonEmpty (NonEmpty(..)) -import Control.Monad.Random.Class (MonadRandom(getRandomR, getRandom)) -import Control.Monad.Random (Rand, evalRand, mkStdGen, StdGen) -import Data.Functor.Compose -import Data.Random.Shuffle.Weighted -import Data.Random.Distribution -import Data.Random.Distribution.Uniform -import Data.Random.Distribution.Uniform.Exclusive -import Data.Random.Sample -import qualified Data.Random.Source as DRS --------------------------------------------------------------------------------- - -instance {-# INCOHERENT #-} (Monad m, MonadRandom m) => DRS.MonadRandom m where - getRandomWord8 = getRandom - getRandomWord16 = getRandom - getRandomWord32 = getRandom - getRandomWord64 = getRandom - getRandomDouble = getRandom - getRandomNByteInteger n = getRandomR (0, 256 ^ n) - -class Choose a where - type RandomResult a - choose :: MonadRandom m => a -> m (RandomResult a) - -newtype ChooseElement a = ChooseElement a - -instance MonoFoldable a => Choose (ChooseElement a) where - type RandomResult (ChooseElement a) = Maybe (Element a) - choose (ChooseElement xs) = do - chosenIdx <- getRandomR (0, olength xs - 1) - let pick _ (Just x) = Just x - pick (x, i) Nothing - | i == chosenIdx = Just x - | otherwise = Nothing - pure $ ofoldr pick Nothing $ zip (toList xs) [0..] - -instance MonoFoldable a => Choose (NonNull a) where - type RandomResult (NonNull a) = Element a - choose - = fmap (fromMaybe (error "unreachable")) -- why not lol - . choose - . ChooseElement - . toNullable - -instance Choose (NonEmpty a) where - type RandomResult (NonEmpty a) = a - choose = choose . fromNonEmpty @[_] - -instance Choose (a, a) where - type RandomResult (a, a) = a - choose (x, y) = choose (x :| [y]) - -newtype Weighted w t a = Weighted (t (w, a)) - deriving (Functor, Foldable) via (t `Compose` (,) w) - -instance Traversable t => Traversable (Weighted w t) where - traverse f (Weighted twa) = Weighted <$> (traverse . traverse) f twa - -evenlyWeighted :: [a] -> Weighted Int [] a -evenlyWeighted = Weighted . itoList - --- | Weight the elements of some functor by a function. Larger values of 'w' per --- its 'Ord' instance will be more likely to be generated -weightedBy :: Functor t => (a -> w) -> t a -> Weighted w t a -weightedBy weighting xs = Weighted $ (weighting &&& id) <$> xs - -instance (Num w, Ord w, Distribution Uniform w, Excludable w) => Choose (Weighted w [] a) where - type RandomResult (Weighted w [] a) = Maybe a - choose (Weighted ws) = sample $ headMay <$> weightedSample 1 ws - -instance (Num w, Ord w, Distribution Uniform w, Excludable w) => Choose (Weighted w NonEmpty a) where - type RandomResult (Weighted w NonEmpty a) = a - choose (Weighted ws) = - sample - $ fromMaybe (error "unreachable") . headMay - <$> weightedSample 1 (toList ws) - -subRand :: MonadRandom m => Rand StdGen a -> m a -subRand sub = evalRand sub . mkStdGen <$> getRandom - --- | Has a @n@ chance of returning 'True' --- --- eg, chance 0.5 will return 'True' half the time -chance - :: (Num w, Ord w, Distribution Uniform w, Excludable w, MonadRandom m) - => w - -> m Bool -chance n = choose $ weightedBy (bool 1 (n * 2)) bools - --- | Choose a random subset of *about* @w@ of the elements of the given --- 'Witherable' structure -chooseSubset :: ( Num w, Ord w, Distribution Uniform w, Excludable w - , Witherable t - , MonadRandom m - ) => w -> t a -> m (t a) -chooseSubset = filterA . const . chance - --------------------------------------------------------------------------------- - -bools :: NonEmpty Bool -bools = True :| [False] |