{-
Copyright (C) 2018 Dr. Alistair Ward
This file is part of BishBosh.
BishBosh is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
BishBosh is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with BishBosh. If not, see .
-}
{- |
[@AUTHOR@] Dr. Alistair Ward
[@DESCRIPTION@]
* The relative values of the various /rank/s of chess-piece.
*
-}
module BishBosh.Attribute.RankValues(
-- * Types
-- ** Data-types
RankValues(),
-- * Constants
tag,
-- * Functions
findRankValue,
calculateMaximumTotalValue,
-- ** Constructor
fromAssocs
) where
import Control.Arrow((***))
import Data.Array.IArray((!))
import qualified BishBosh.Attribute.Rank as Attribute.Rank
import qualified BishBosh.Data.Exception as Data.Exception
import qualified BishBosh.Data.Num as Data.Num
import qualified BishBosh.Property.ShowFloat as Property.ShowFloat
import qualified BishBosh.Text.ShowList as Text.ShowList
import qualified Control.DeepSeq
import qualified Control.Exception
import qualified Data.Array.IArray
import qualified Data.Default
import qualified Data.List
import qualified Data.Set
import qualified Text.XML.HXT.Arrow.Pickle as HXT
-- | Used to qualify XML.
tag :: String
tag = "rankValues"
{- |
* The constant value associated with each /rank/; the higher, the more valuable it is considered to be.
* N.B.: only relative values are significant; the absolute value associated with any /rank/ is irrelevant, but typically @Pawn = 1@.
* CAVEAT: a @King@ can never be taken, but assigning the value /infinity/ creates problems, so typically it has the value @0@.
-}
newtype RankValues rankValue = MkRankValues {
deconstruct :: Attribute.Rank.ByRank rankValue
} deriving (Eq, Read, Show)
instance Real rankValue => Property.ShowFloat.ShowFloat (RankValues rankValue) where
showsFloat fromDouble = Text.ShowList.showsAssociationList' . map (show *** fromDouble . realToFrac) . Data.Array.IArray.assocs . deconstruct
-- Derived from Larry Kaufman's values; .
instance (
Fractional rankValue,
Ord rankValue,
Show rankValue
) => Data.Default.Default (RankValues rankValue) where
def = fromAssocs [
(
Attribute.Rank.Pawn, 0.1
), (
Attribute.Rank.Rook, 0.525
), (
Attribute.Rank.Knight, 0.35
), (
Attribute.Rank.Bishop, 0.35
), (
Attribute.Rank.Queen, 1
), (
Attribute.Rank.King, 0 -- N.B.: move-selection is independent of this value (since it can't be taken), so it can be defined arbitrarily.
)
]
instance Control.DeepSeq.NFData rankValue => Control.DeepSeq.NFData (RankValues rankValue) where
rnf (MkRankValues byRank) = Control.DeepSeq.rnf byRank
instance (
Fractional rankValue,
HXT.XmlPickler rankValue,
Ord rankValue,
Show rankValue
) => HXT.XmlPickler (RankValues rankValue) where
xpickle = HXT.xpDefault Data.Default.def . HXT.xpWrap (
fromAssocs, -- Construct from an association-list.
Data.Array.IArray.assocs . deconstruct -- Deconstruct to an association-list.
) . HXT.xpList1 . HXT.xpElem tag $ HXT.xpickle {-rank-} `HXT.xpPair` HXT.xpAttr "value" HXT.xpickle
-- | Smart-constructor.
fromAssocs :: (
Fractional rankValue,
Ord rankValue,
Show rankValue
) => [(Attribute.Rank.Rank, rankValue)] -> RankValues rankValue
fromAssocs assocs
| not $ Data.Set.null undefinedRanks = Control.Exception.throw . Data.Exception.mkInsufficientData . showString "BishBosh.Attribute.RankValues.fromAssocs:\tranks" . Text.ShowList.showsAssociation $ shows (Data.Set.toList undefinedRanks) " are undefined."
| any (
not . Data.Num.inClosedUnitInterval . snd {-rank-value-}
) assocs = Control.Exception.throw . Data.Exception.mkOutOfBounds . showString "BishBosh.Attribute.RankValues.fromAssocs:\tall values must be within the closed unit-interval, [0,1]; " $ shows assocs "."
| otherwise = MkRankValues byRank
where
undefinedRanks = Data.Set.fromAscList Attribute.Rank.range `Data.Set.difference` Data.Set.fromList (map fst assocs)
byRank = Data.Array.IArray.array (minBound, maxBound) assocs
-- | Query.
findRankValue :: Attribute.Rank.Rank -> RankValues rankValue -> rankValue
findRankValue rank (MkRankValues byRank) = byRank ! rank
{- |
* The maximum total rank-value one side can have.
* CAVEAT: assumes that zero pieces have been captured, all @Pawn@s have been queened, & that this is the most valuable /rank/ of /piece/.
-}
calculateMaximumTotalValue :: Num rankValue => RankValues rankValue -> rankValue
calculateMaximumTotalValue (MkRankValues byRank) = 9 {-accounting for all possible promotions-} * (byRank ! Attribute.Rank.Queen) + 2 * Data.List.foldl' (
\acc -> (+ acc) . (byRank !)
) 0 Attribute.Rank.flank