feat(xanthous) Generate random volume+density for items r/2679

Generate random volumes and densities for items based on the ranges for
those two quantities in the raw when building instances of items.

Since this is the first time creating an item is impure, this also lifts
entity generation into a (random) monadic context

Change-Id: I2de4880e8144f7ff9e1304eb32806ed1d7affa18
Reviewed-on: https://cl.tvl.fyi/c/depot/+/3226
Reviewed-by: grfn <grfn@gws.fyi>
Tested-by: BuildkiteCI

9 files changed, 108 insertions, 25 deletions

diff --git a/users/grfn/xanthous/src/Xanthous/Data.hs b/users/grfn/xanthous/src/Xanthous/Data.hs
index 89d0993b4e..ba6f98558a 100644
--- a/users/grfn/xanthous/src/Xanthous/Data.hs
+++ b/users/grfn/xanthous/src/Xanthous/Data.hs
@@ -6,6 +6,8 @@
 {-# LANGUAGE TemplateHaskell        #-}
 {-# LANGUAGE NoTypeSynonymInstances #-}
 {-# LANGUAGE DuplicateRecordFields  #-}
+{-# LANGUAGE QuantifiedConstraints  #-}
+{-# LANGUAGE UndecidableInstances   #-}
 --------------------------------------------------------------------------------
 -- | Common data types for Xanthous
 --------------------------------------------------------------------------------
@@ -117,6 +119,8 @@ import           Xanthous.Util (EqEqProp(..), EqProp, between)
 import           Xanthous.Util.QuickCheck (GenericArbitrary(..))
 import           Xanthous.Orphans ()
 import           Xanthous.Util.Graphics
+import Data.Random (Distribution)
+import Data.Coerce
 --------------------------------------------------------------------------------
 
 -- | opposite ∘ opposite ≡ id
@@ -495,6 +499,11 @@ newtype Per a b = Rate Double
   deriving (Arbitrary, Num, Ord, Enum, Real, Fractional, ToJSON, FromJSON)
        via Double
   deriving (Semigroup, Monoid) via Product Double
+deriving via Double
+  instance ( Distribution d Double
+           , forall xx yy. Coercible xx yy => Coercible (d xx) (d yy)
+           )
+  => Distribution d (Per a b)
 
 invertRate :: a `Per` b -> b `Per` a
 invertRate (Rate p) = Rate $ 1 / p
@@ -529,6 +538,12 @@ newtype Square a = Square a
            )
        via a
 
+deriving via (a :: Type)
+  instance ( Distribution d a
+           , forall xx yy. Coercible xx yy => Coercible (d xx) (d yy)
+           )
+  => Distribution d (Square a)
+
 newtype Cubic a = Cubic a
   deriving stock (Show, Eq, Generic)
   deriving anyclass (NFData, CoArbitrary, Function)
@@ -537,6 +552,12 @@ newtype Cubic a = Cubic a
            )
        via a
 
+deriving via (a :: Type)
+  instance ( Distribution d a
+           , forall xx yy. Coercible xx yy => Coercible (d xx) (d yy)
+           )
+  => Distribution d (Cubic a)
+
 --------------------------------------------------------------------------------
 
 newtype Ticks = Ticks Word
@@ -546,6 +567,11 @@ newtype Ticks = Ticks Word
   deriving (Semigroup, Monoid) via (Sum Word)
   deriving Scalar via ScalarIntegral Ticks
   deriving Arbitrary via GenericArbitrary Ticks
+deriving via Word
+  instance ( Distribution d Word
+           , forall xx yy. Coercible xx yy => Coercible (d xx) (d yy)
+           )
+  => Distribution d Ticks
 
 newtype Tiles = Tiles Double
   deriving stock (Show, Eq, Generic)
@@ -553,6 +579,11 @@ newtype Tiles = Tiles Double
   deriving (Num, Ord, Enum, Real, ToJSON, FromJSON, Scalar) via Double
   deriving (Semigroup, Monoid) via (Sum Double)
   deriving Arbitrary via GenericArbitrary Tiles
+deriving via Double
+  instance ( Distribution d Double
+           , forall xx yy. Coercible xx yy => Coercible (d xx) (d yy)
+           )
+  => Distribution d Tiles
 
 type TicksPerTile = Ticks `Per` Tiles
 type TilesPerTick = Tiles `Per` Ticks
diff --git a/users/grfn/xanthous/src/Xanthous/Entities/Creature.hs b/users/grfn/xanthous/src/Xanthous/Entities/Creature.hs
index e95e9f0b98..f23cf25b43 100644
--- a/users/grfn/xanthous/src/Xanthous/Entities/Creature.hs
+++ b/users/grfn/xanthous/src/Xanthous/Entities/Creature.hs
@@ -33,6 +33,7 @@ import           Test.QuickCheck
 import           Test.QuickCheck.Arbitrary.Generic
 import           Data.Aeson.Generic.DerivingVia
 import           Data.Aeson (ToJSON, FromJSON)
+import           Control.Monad.Random (MonadRandom)
 --------------------------------------------------------------------------------
 import           Xanthous.AI.Gormlak
 import           Xanthous.Entities.RawTypes hiding
@@ -74,11 +75,11 @@ instance Entity Creature where
 
 --------------------------------------------------------------------------------
 
-newWithType :: CreatureType -> Creature
+newWithType :: MonadRandom m => CreatureType -> m Creature
 newWithType _creatureType =
   let _hitpoints = _creatureType ^. maxHitpoints
       _hippocampus = initialHippocampus
-  in Creature {..}
+  in pure Creature {..}
 
 damage :: Hitpoints -> Creature -> Creature
 damage amount = hitpoints %~ \hp ->
diff --git a/users/grfn/xanthous/src/Xanthous/Entities/Item.hs b/users/grfn/xanthous/src/Xanthous/Entities/Item.hs
index b50a5eab80..6647c42731 100644
--- a/users/grfn/xanthous/src/Xanthous/Entities/Item.hs
+++ b/users/grfn/xanthous/src/Xanthous/Entities/Item.hs
@@ -1,49 +1,63 @@
 {-# LANGUAGE TemplateHaskell #-}
 {-# LANGUAGE StandaloneDeriving #-}
+{-# LANGUAGE RecordWildCards #-}
 --------------------------------------------------------------------------------
 module Xanthous.Entities.Item
   ( Item(..)
   , itemType
+  , density
+  , volume
   , newWithType
   , isEdible
+  , weight
   ) where
 --------------------------------------------------------------------------------
 import           Xanthous.Prelude
-import           Test.QuickCheck
+import           Test.QuickCheck (Arbitrary, CoArbitrary, Function)
 import           Data.Aeson (ToJSON, FromJSON)
 import           Data.Aeson.Generic.DerivingVia
+import           Control.Monad.Random (MonadRandom)
 --------------------------------------------------------------------------------
-import           Xanthous.Entities.RawTypes hiding (Item, description, isEdible)
+import           Xanthous.Entities.RawTypes (ItemType)
 import qualified Xanthous.Entities.RawTypes as Raw
 import           Xanthous.Game.State
+import           Xanthous.Data (Grams, Per, Cubic, Meters, (|*|))
+import           Xanthous.Util.QuickCheck (GenericArbitrary(GenericArbitrary))
+import           Xanthous.Random (choose, FiniteInterval(..))
 --------------------------------------------------------------------------------
 
 data Item = Item
   { _itemType :: ItemType
+  , _density  :: Grams `Per` Cubic Meters
+  , _volume   :: Cubic Meters
   }
   deriving stock (Eq, Show, Ord, Generic)
   deriving anyclass (NFData, CoArbitrary, Function)
   deriving Draw via DrawRawChar "_itemType" Item
+  deriving Arbitrary via GenericArbitrary Item
   deriving (ToJSON, FromJSON)
        via WithOptions '[ FieldLabelModifier '[Drop 1] ]
                        Item
 makeLenses ''Item
 
-{-# ANN Item ("HLint: ignore Use newtype instead of data" :: String )#-}
-
 -- deriving via (Brainless Item) instance Brain Item
 instance Brain Item where step = brainVia Brainless
 
-instance Arbitrary Item where
-  arbitrary = Item <$> arbitrary
-
 instance Entity Item where
   description = view $ itemType . Raw.description
   entityChar = view $ itemType . Raw.char
   entityCollision = const Nothing
 
-newWithType :: ItemType -> Item
-newWithType = Item
+newWithType :: MonadRandom m => ItemType -> m Item
+newWithType _itemType = do
+  _density <- choose . FiniteInterval $ _itemType ^. Raw.density
+  _volume  <- choose . FiniteInterval $ _itemType ^. Raw.volume
+  pure Item {..}
 
 isEdible :: Item -> Bool
 isEdible = Raw.isEdible . view itemType
+
+-- | The weight of this item, calculated by multiplying its volume by the
+-- density of its material
+weight :: Item -> Grams
+weight item = (item ^. density) |*| (item ^. volume)
diff --git a/users/grfn/xanthous/src/Xanthous/Entities/RawTypes.hs b/users/grfn/xanthous/src/Xanthous/Entities/RawTypes.hs
index 88070ed7b8..b0fb5e086e 100644
--- a/users/grfn/xanthous/src/Xanthous/Entities/RawTypes.hs
+++ b/users/grfn/xanthous/src/Xanthous/Entities/RawTypes.hs
@@ -31,6 +31,7 @@ module Xanthous.Entities.RawTypes
   , HasAttackMessage(..)
   , HasChar(..)
   , HasDamage(..)
+  , HasDensity(..)
   , HasDescription(..)
   , HasEatMessage(..)
   , HasEdible(..)
@@ -42,6 +43,7 @@ module Xanthous.Entities.RawTypes
   , HasName(..)
   , HasSayVerb(..)
   , HasSpeed(..)
+  , HasVolume(..)
   , HasWieldable(..)
   ) where
 --------------------------------------------------------------------------------
diff --git a/users/grfn/xanthous/src/Xanthous/Entities/Raws.hs b/users/grfn/xanthous/src/Xanthous/Entities/Raws.hs
index d4cae7ccc2..441e870160 100644
--- a/users/grfn/xanthous/src/Xanthous/Entities/Raws.hs
+++ b/users/grfn/xanthous/src/Xanthous/Entities/Raws.hs
@@ -12,6 +12,7 @@ import           Data.FileEmbed
 import qualified Data.Yaml as Yaml
 import           Xanthous.Prelude
 import           System.FilePath.Posix
+import           Control.Monad.Random (MonadRandom)
 --------------------------------------------------------------------------------
 import           Xanthous.Entities.RawTypes
 import           Xanthous.Game.State
@@ -52,8 +53,8 @@ rawsWithType = mapFromList . itoListOf (ifolded . _RawType) $ raws
 
 --------------------------------------------------------------------------------
 
-entityFromRaw :: EntityRaw -> SomeEntity
+entityFromRaw :: MonadRandom m => EntityRaw -> m SomeEntity
 entityFromRaw (Creature creatureType)
-  = SomeEntity $ Creature.newWithType creatureType
+  = SomeEntity <$> Creature.newWithType creatureType
 entityFromRaw (Item itemType)
-  = SomeEntity $ Item.newWithType itemType
+  = SomeEntity <$> Item.newWithType itemType
diff --git a/users/grfn/xanthous/src/Xanthous/Generators/Level/LevelContents.hs b/users/grfn/xanthous/src/Xanthous/Generators/Level/LevelContents.hs
index 7582ae2758..3cad569336 100644
--- a/users/grfn/xanthous/src/Xanthous/Generators/Level/LevelContents.hs
+++ b/users/grfn/xanthous/src/Xanthous/Generators/Level/LevelContents.hs
@@ -100,7 +100,7 @@ tutorialMessage cells characterPosition = do
 
 randomEntities
   :: forall entity raw m. (MonadRandom m, RawType raw)
-  => (raw -> entity)
+  => (raw -> m entity)
   -> (Float, Float)
   -> Cells
   -> m (EntityMap entity)
@@ -114,7 +114,7 @@ randomEntities newWithType sizeRange cells =
       entities <- for [0..numEntities] $ const $ do
         pos <- randomPosition cells
         raw <- choose raws
-        let entity = newWithType raw
+        entity <- newWithType raw
         pure (pos, entity)
       pure $ _EntityMap # entities
 
diff --git a/users/grfn/xanthous/src/Xanthous/Random.hs b/users/grfn/xanthous/src/Xanthous/Random.hs
index 72bdb63d2c..329b321b8b 100644
--- a/users/grfn/xanthous/src/Xanthous/Random.hs
+++ b/users/grfn/xanthous/src/Xanthous/Random.hs
@@ -13,6 +13,7 @@ module Xanthous.Random
   , chance
   , chooseSubset
   , chooseRange
+  , FiniteInterval(..)
   ) where
 --------------------------------------------------------------------------------
 import           Xanthous.Prelude
@@ -28,7 +29,7 @@ import           Data.Random.Distribution.Uniform.Exclusive
 import           Data.Random.Sample
 import qualified Data.Random.Source as DRS
 import           Data.Interval ( Interval, lowerBound', Extended (Finite)
-                               , upperBound', Boundary (Closed)
+                               , upperBound', Boundary (Closed), lowerBound, upperBound
                                )
 --------------------------------------------------------------------------------
 
@@ -128,7 +129,9 @@ chooseRange
   :: ( MonadRandom m
     , Distribution Uniform n
     , Enum n
-    , Bounded n, Show n, Ord n)
+    , Bounded n
+    , Ord n
+    )
   => Interval n
   -> m (Maybe n)
 chooseRange int = traverse sample distribution
@@ -149,6 +152,33 @@ chooseRange int = traverse sample distribution
       | lowerR <= upperR = Just $ Uniform lowerR upperR
       | otherwise = Nothing
 
+instance ( Distribution Uniform n
+         , Enum n
+         , Bounded n
+         , Ord n
+         )
+         => Choose (Interval n) where
+  type RandomResult (Interval n) = n
+  choose = fmap (fromMaybe $ error "Invalid interval") . chooseRange
+
+newtype FiniteInterval a
+  = FiniteInterval { unwrapFiniteInterval :: (Interval a) }
+
+instance ( Distribution Uniform n
+         , Ord n
+         )
+         => Choose (FiniteInterval n) where
+  type RandomResult (FiniteInterval n) = n
+  -- TODO broken with open/closed right now
+  choose
+    = sample
+    . uncurry Uniform
+    . over both getFinite
+    . (lowerBound &&& upperBound)
+    . unwrapFiniteInterval
+    where
+      getFinite (Finite x) = x
+      getFinite _ = error "Infinite value"
 
 --------------------------------------------------------------------------------
 
diff --git a/users/grfn/xanthous/src/Xanthous/Util.hs b/users/grfn/xanthous/src/Xanthous/Util.hs
index 189e781e6c..fea9c07c12 100644
--- a/users/grfn/xanthous/src/Xanthous/Util.hs
+++ b/users/grfn/xanthous/src/Xanthous/Util.hs
@@ -48,7 +48,7 @@ import           Data.Proxy
 import qualified Data.Vector as V
 import           Data.Semigroup (Max(..), Min(..))
 import           Data.Semigroup.Foldable
-import Control.Monad.State.Class
+import           Control.Monad.State.Class
 --------------------------------------------------------------------------------
 
 newtype EqEqProp a = EqEqProp a
diff --git a/users/grfn/xanthous/test/Xanthous/Game/StateSpec.hs b/users/grfn/xanthous/test/Xanthous/Game/StateSpec.hs
index 3267d8ef9e..b02abb04b4 100644
--- a/users/grfn/xanthous/test/Xanthous/Game/StateSpec.hs
+++ b/users/grfn/xanthous/test/Xanthous/Game/StateSpec.hs
@@ -5,6 +5,8 @@ import           Test.Prelude
 --------------------------------------------------------------------------------
 import           Xanthous.Game.State
 import           Xanthous.Entities.Raws (raws, entityFromRaw)
+import Control.Monad.Random (evalRandT)
+import System.Random (getStdGen)
 --------------------------------------------------------------------------------
 
 main :: IO ()
@@ -13,13 +15,15 @@ main = defaultMain test
 test :: TestTree
 test = testGroup "Xanthous.Game.StateSpec"
   [ testGroup "entityTypeName"
-    [ testCase "for a creature" $
+    [ testCase "for a creature" $ do
         let gormlakRaw = raws ^?! ix "gormlak"
-            creature = entityFromRaw gormlakRaw
-        in entityTypeName creature @?= "Creature"
-    , testCase "for an item" $
+        creature <- runRand $ entityFromRaw gormlakRaw
+        entityTypeName creature @?= "Creature"
+    , testCase "for an item" $ do
         let stickRaw = raws ^?! ix "stick"
-            item = entityFromRaw stickRaw
-        in entityTypeName item @?= "Item"
+        item <- runRand $ entityFromRaw stickRaw
+        entityTypeName item @?= "Item"
     ]
   ]
+  where
+    runRand x = evalRandT x =<< getStdGen