X-Git-Url: http://gitweb.michael.orlitzky.com/?a=blobdiff_plain;f=src%2FMisc.hs;h=48482b4f69a2cfe580b8b34a605beae82565168b;hb=effb6b9a8716ce58fed6c8260c57164601a7df30;hp=6364e95e2c6f3b97794a609bbc7df6c40bd9b65a;hpb=89b8b6e94fcc944a1f4611811265f3c6217af850;p=spline3.git

diff --git a/src/Misc.hs b/src/Misc.hs
index 6364e95..48482b4 100644
--- a/src/Misc.hs
+++ b/src/Misc.hs
@@ -7,6 +7,15 @@ where
 -- | The standard factorial function. See
 --   <http://www.willamette.edu/~fruehr/haskell/evolution.html> for
 --   possible improvements.
+--
+--   Examples:
+--
+--   >>> factorial 0
+--   1
+--
+--   >>> factorial 4
+--   24
+--
 factorial :: Int -> Int
 factorial n
     | n <= 1 = 1
@@ -18,3 +27,13 @@ factorial n
 --   one-dimensional one.
 flatten :: [[[a]]] -> [a]
 flatten xs = concat $ concat xs
+
+
+-- | Takes a list, and returns True if its elements are pairwise
+--   equal. Returns False otherwise.
+all_equal :: (Eq a) => [a] -> Bool
+all_equal xs =
+    all (== first_element) other_elements
+    where
+      first_element  = head xs
+      other_elements = tail xs