src/Linear/Vector.hs: add a Vec0 type.

[numerical-analysis.git] / src / Linear / Vector.hs

diff --git a/src/Linear/Vector.hs b/src/Linear/Vector.hs
index 42d47a39e58670136b5300dd1f83f007ce85fc2e..c9307153cc65330b2e0ec8e4f5eeec85d933607b 100644 (file)
--- a/src/Linear/Vector.hs
+++ b/src/Linear/Vector.hs
@@ -1,31 +1,44 @@
 {-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE NoImplicitPrelude #-}
+{-# LANGUAGE NoMonomorphismRestriction #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE TypeFamilies #-}
 
-module Linear.Vector
+module Linear.Vector (
+  module Data.Vector.Fixed.Boxed,
+  Vec0,
+  Vec1,
+  (!?),
+  delete,
+  element_sum )
 where
 
+import qualified Algebra.Additive as Additive ( C )
+import qualified Algebra.Ring as Ring ( C )
 import Data.Vector.Fixed (
   Dim,
   N1,
-  N4,
-  N5,
   S,
   Vector(..),
+  Z,
   fromList,
-  toList,
-  )
-import qualified Data.Vector.Fixed as V (
+  toList )
+import Data.Vector.Fixed (
   (!),
-  length,
-  )
-import Data.Vector.Fixed.Boxed
+  foldl,
+  length )
+import Data.Vector.Fixed.Boxed (
+  Vec,
+  Vec2,
+  Vec3,
+  Vec4,
+  Vec5 )
+import NumericPrelude hiding ( abs, length, foldl )
 
+type Vec0 = Vec Z
 type Vec1 = Vec N1
-type Vec4 = Vec N4
-type Vec5 = Vec N5
 
 
 
@@ -42,8 +55,8 @@ type Vec5 = Vec N5
 --
 (!?) :: (Vector v a) => v a -> Int -> Maybe a
 (!?) v1 idx
-  | idx < 0 || idx >= V.length v1 = Nothing
-  | otherwise                     = Just $ v1 V.! idx
+  | idx < 0 || idx >= length v1 = Nothing
+  | otherwise                   = Just $ v1 ! idx
 
 
 -- | Remove an element of the given vector.
@@ -55,9 +68,28 @@ type Vec5 = Vec N5
 --   >>> delete b 1 :: Vec2 Int
 --   fromList [1,3]
 --
-delete :: (Vector v a, Vector w a, Dim v ~ S (Dim w)) => v a -> Int -> w a
+delete :: (Vector v a,
+           Vector w a,
+           Dim v ~ S (Dim w))
+       => v a
+       -> Int
+       -> w a
 delete v1 idx =
-  fromList $ (lhalf ++ rhalf')
+  fromList (lhalf ++ rhalf')
   where
     (lhalf, rhalf) = splitAt idx (toList v1)
     rhalf' = tail rhalf
+
+
+-- | We provide our own sum because sum relies on a Num instance
+--   from the Prelude that we don't have.
+--
+--   Examples:
+--
+--   >>> import Data.Vector.Fixed (mk3)
+--   >>> let b = mk3 1 2 3 :: Vec3 Int
+--   >>> element_sum b
+--   6
+--
+element_sum :: (Additive.C a, Ring.C a, Vector v a) => v a -> a
+element_sum = foldl (+) (fromInteger 0)