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   N1,
  13   N4,
  14   N5,
  15   S,
  16   Vector(..),
  17   fromList,
  18   toList,
  19   )
  20 import qualified Data.Vector.Fixed as V (
  21   length,
  22   )
  23 import Data.Vector.Fixed.Boxed
  24
  25 type Vec1 = Vec N1
  26 type Vec4 = Vec N4
  27 type Vec5 = Vec N5
  28
  29
  30 -- | Unsafe indexing.
  31 --
  32 --   Examples:
  33 --
  34 --   >>> import Data.Vector.Fixed (mk2)
  35 --   >>> let v1 = mk2 1 2 :: Vec2 Int
  36 --   >>> v1 ! 1
  37 --   2
  38 --
  39 (!) :: (Vector v a) => v a -> Int -> a
  40 (!) v1 idx = (toList v1) !! idx
  41
  42 -- | Safe indexing.
  43 --
  44 --   Examples:
  45 --
  46 --   >>> import Data.Vector.Fixed (mk3)
  47 --   >>> let v1 = mk3 1 2 3 :: Vec3 Int
  48 --   >>> v1 !? 2
  49 --   Just 3
  50 --   >>> v1 !? 3
  51 --   Nothing
  52 --
  53 (!?) :: (Vector v a) => v a -> Int -> Maybe a
  54 (!?) v1 idx
  55   | idx < 0 || idx >= V.length v1 = Nothing
  56   | otherwise                     = Just $ v1 ! idx
  57
  58
  59 -- | Remove an element of the given vector.
  60 --
  61 --   Examples:
  62 --
  63 --   >>> import Data.Vector.Fixed (mk3)
  64 --   >>> let b = mk3 1 2 3 :: Vec3 Int
  65 --   >>> delete b 1 :: Vec2 Int
  66 --   fromList [1,3]
  67 --
  68 delete :: (Vector v a, Vector w a, Dim v ~ S (Dim w)) => v a -> Int -> w a
  69 delete v1 idx =
  70   fromList $ (lhalf ++ rhalf')
  71   where
  72     (lhalf, rhalf) = splitAt idx (toList v1)
  73     rhalf' = tail rhalf