X-Git-Url: http://gitweb.michael.orlitzky.com/?a=blobdiff_plain;f=src%2FMisc.hs;h=09773bf56655b13453ed7dff6e49b160bf70eb11;hb=0d037f5f0829d9ee7fcccc58570305623665f52e;hp=b1cb1affcce0a53463c5f9ae400c5da27fabd157;hpb=3f7331f579118687cd73b977ce6aa7d401f88a09;p=spline3.git

diff --git a/src/Misc.hs b/src/Misc.hs
index b1cb1af..09773bf 100644
--- a/src/Misc.hs
+++ b/src/Misc.hs
@@ -1,14 +1,24 @@
+{-# LANGUAGE BangPatterns #-}
+
 -- | The Misc module contains helper functions that seem out of place
 --   anywhere else.
-module Misc
+--
+module Misc (
+  all_equal,
+  disjoint,
+  factorial,
+  flatten,
+  misc_properties,
+  misc_tests,
+  transpose_xz )
 where
 
-import qualified Data.Vector as V (Vector, elem, empty, filter)
-import Test.Framework (Test, testGroup)
-import Test.Framework.Providers.HUnit (testCase)
-import Test.Framework.Providers.QuickCheck2 (testProperty)
-import Test.HUnit (Assertion, assertEqual)
-import Test.QuickCheck
+import qualified Data.Vector as V ( Vector, elem, empty, filter )
+import Test.Framework ( Test, testGroup )
+import Test.Framework.Providers.HUnit ( testCase )
+import Test.Framework.Providers.QuickCheck2 ( testProperty )
+import Test.HUnit ( Assertion, assertEqual )
+import Test.QuickCheck ( Property, (==>) )
 
 
 -- | The standard factorial function. See
@@ -24,11 +34,12 @@ import Test.QuickCheck
 --   24
 --
 factorial :: Int -> Int
-factorial n
-    | n <= 1 = 1
-    | n > 20 = error "integer overflow in factorial function"
-    | otherwise = product [1..n]
-
+factorial !n =
+  go 1 n
+  where
+    go !acc !i
+      | i <= 1    = acc
+      | otherwise = go (acc * i) (i - 1)
 
 -- | Takes a three-dimensional list, and flattens it into a
 --   one-dimensional one.
@@ -58,12 +69,13 @@ transpose_xz m =
 
 -- | Takes a list, and returns True if its elements are pairwise
 --   equal. Returns False otherwise.
+--
+--   Only used in tests.
+--
 all_equal :: (Eq a) => [a] -> Bool
-all_equal xs =
-    all (== first_element) other_elements
-    where
-      first_element  = head xs
-      other_elements = tail xs
+all_equal [] = True -- Vacuously
+all_equal (x:xs) = all (== x) xs
+
 
 
 -- | Returns 'True' if the vectors xs and ys are disjoint, 'False'
@@ -80,6 +92,8 @@ all_equal xs =
 --   >>> disjoint xs ys
 --   False
 --
+--   Only used in tests.
+--
 disjoint :: (Eq a) => V.Vector a -> V.Vector a -> Bool
 disjoint xs ys =
   intersect xs ys == V.empty