From 34924012e69f77b50b95c0a80d1822c8ea3cf593 Mon Sep 17 00:00:00 2001
From: Tim Makarios <tjm1983@gmail.com>
Date: Fri, 4 Apr 2014 17:13:41 +1300
Subject: [PATCH] Test if a ValueSimplex is empty

---
 Test/ValueSimplex.hs | 5 +++++
 ValueSimplex.hs      | 3 +++
 2 files changed, 8 insertions(+)

diff --git a/Test/ValueSimplex.hs b/Test/ValueSimplex.hs
index 54e64e4..f28d0ab 100644
--- a/Test/ValueSimplex.hs
+++ b/Test/ValueSimplex.hs
@@ -91,6 +91,10 @@ prop_nodes_fromFunction_Double :: (Arbitrary a, CoArbitrary a, Ord a, Show a)
   => Blind (a -> a -> Double) -> Property
 prop_nodes_fromFunction_Double = nodes_fromFunction
 
+prop_empty :: (Arbitrary a, CoArbitrary a, Ord a, Show a)
+  => Blind (a -> a -> Double) -> Bool
+prop_empty (Blind f) = isEmpty $ fromFunction f Set.empty
+
 --------------------------------------------------------------------------------
 
 fromFunction_vsLookup :: (Ord a, Eq b, Num b) => ValueSimplex a b -> Bool
@@ -108,6 +112,7 @@ exact_ValueSimplex_validity_tests = testList
   [ printTestCase "fromFunction_vsLookup" . fromFunction_vsLookup
   , printTestCase "values_positive" . values_positive
   , printTestCase "non_degenerate" . non_degenerate
+  , printTestCase "non-empty" . not . isEmpty
   ]
 
 prop_exact_ValueSimplex_validity_tests_Double :: (Ord a, Show a)
diff --git a/ValueSimplex.hs b/ValueSimplex.hs
index 4860215..cf61930 100644
--- a/ValueSimplex.hs
+++ b/ValueSimplex.hs
@@ -26,6 +26,9 @@ data VSStatus
 nodes :: Ord a => ValueSimplex a b -> Set a
 nodes vs = Set.map fst $ Map.keysSet $ vsMap vs
 
+isEmpty :: Ord a => ValueSimplex a b -> Bool
+isEmpty = Set.null . nodes
+
 pairUp :: a -> b -> (a, b)
 pairUp = curry id
 
-- 
2.11.4.GIT