src/Linear/Vector.hs

   1 {-# LANGUAGE FlexibleContexts #-}
   2 {-# LANGUAGE FlexibleInstances #-}
   3 {-# LANGUAGE MultiParamTypeClasses #-}
   4 {-# LANGUAGE ScopedTypeVariables #-}
   5 {-# LANGUAGE TypeFamilies #-}
   6
   7 module Linear.Vector
   8 where
   9
  10 import Data.Vector.Fixed (
  11   Dim,
  12   Fun(..),
  13   N1,
  14   N2,
  15   N3,
  16   N4,
  17   N5,
  18   S,
  19   Vector(..),
  20   construct,
  21   fromList,
  22   inspect,
  23   toList,
  24   )
  25 import qualified Data.Vector.Fixed as V (
  26   length,
  27   )
  28 import Data.Vector.Fixed.Boxed
  29
  30 type Vec1 = Vec N1
  31 type Vec4 = Vec N4
  32 type Vec5 = Vec N5
  33
  34 -- * Low-dimension vector wrappers.
  35 --
  36 -- These wrappers are instances of 'Vector', so they inherit all of
  37 -- the userful instances defined above. But, they use fixed
  38 -- constructors, so you can pattern match out the individual
  39 -- components.
  40
  41 data D1 a = D1 a deriving (Show, Eq)
  42 type instance Dim D1 = N1
  43 instance Vector D1 a where
  44   inspect (D1 x) (Fun f) = f x
  45   construct = Fun D1
  46
  47 data D2 a = D2 a a deriving (Show, Eq)
  48 type instance Dim D2 = N2
  49 instance Vector D2 a where
  50   inspect (D2 x y) (Fun f) = f x y
  51   construct = Fun D2
  52
  53 data D3 a = D3 a a a deriving (Show, Eq)
  54 type instance Dim D3 = N3
  55 instance Vector D3 a where
  56   inspect (D3 x y z) (Fun f) = f x y z
  57   construct = Fun D3
  58
  59 data D4 a = D4 a a a a deriving (Show, Eq)
  60 type instance Dim D4 = N4
  61 instance Vector D4 a where
  62   inspect (D4 w x y z) (Fun f) = f w x y z
  63   construct = Fun D4
  64
  65
  66 -- | Unsafe indexing.
  67 --
  68 --   Examples:
  69 --
  70 --   >>> let v1 = D2 1 2
  71 --   >>> v1 ! 1
  72 --   2
  73 --
  74 (!) :: (Vector v a) => v a -> Int -> a
  75 (!) v1 idx = (toList v1) !! idx
  76
  77 -- | Safe indexing.
  78 --
  79 --   Examples:
  80 --
  81 --   >>> let v1 = D3 1 2 3
  82 --   >>> v1 !? 2
  83 --   Just 3
  84 --   >>> v1 !? 3
  85 --   Nothing
  86 --
  87 (!?) :: (Vector v a) => v a -> Int -> Maybe a
  88 (!?) v1 idx
  89   | idx < 0 || idx >= V.length v1 = Nothing
  90   | otherwise                     = Just $ v1 ! idx
  91
  92
  93 -- | Remove an element of the given vector.
  94 --
  95 --   Examples:
  96 --
  97 --   >>> let b = D3 1 2 3
  98 --   >>> delete b 1 :: D2 Int
  99 --   D2 1 3
 100 --
 101 delete :: (Vector v a, Vector w a, Dim v ~ S (Dim w)) => v a -> Int -> w a
 102 delete v1 idx =
 103   fromList $ (lhalf ++ rhalf')
 104   where
 105     (lhalf, rhalf) = splitAt idx (toList v1)
 106     rhalf' = tail rhalf