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