[commit: containers] master: Int{Set.Map}.delete{Min, Max} doesn't fail on empty. (f461aea)

[Paolo Capriotti]

Repository : ssh://darcs.haskell.org//srv/darcs/packages/containers

On branch  : master

http://hackage.haskell.org/trac/ghc/changeset/f461aea96e8294a93264fcd09152f2ebef1cd531

>---------------------------------------------------------------

commit f461aea96e8294a93264fcd09152f2ebef1cd531
Author: Milan Straka <fox at ucw.cz>
Date:   Mon Dec 5 22:14:46 2011 +0100

    Int{Set.Map}.delete{Min,Max} doesn't fail on empty.
    
    Make Int{Map,Set}.delete{Min,Max} behave like {Map,Set}.delete{Min,Max}.
    * Old behaviour: Int{Set,Map}.delete{Min,Max} empty ==> error
    * New behaviour: Int{Set,Map}.delete{Min,Max} empty ==  empty

>---------------------------------------------------------------

 Data/IntMap/Base.hs        |    4 ++--
 Data/IntSet.hs             |    4 ++--
 tests/intmap-properties.hs |    2 ++
 3 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/Data/IntMap/Base.hs b/Data/IntMap/Base.hs
index c8c96c2..0ca3480 100644
--- a/Data/IntMap/Base.hs
+++ b/Data/IntMap/Base.hs
@@ -987,12 +987,12 @@ findMax (Bin _ m l r)
 -- | /O(log n)/. Delete the minimal key. An error is thrown if the IntMap is already empty.
 -- Note, this is not the same behavior Map.
 deleteMin :: IntMap a -> IntMap a
-deleteMin = maybe (error "deleteMin: empty map has no minimal element") snd . minView
+deleteMin = maybe Nil snd . minView
 
 -- | /O(log n)/. Delete the maximal key. An error is thrown if the IntMap is already empty.
 -- Note, this is not the same behavior Map.
 deleteMax :: IntMap a -> IntMap a
-deleteMax = maybe (error "deleteMax: empty map has no maximal element") snd . maxView
+deleteMax = maybe Nil snd . maxView
 
 
 {--------------------------------------------------------------------
diff --git a/Data/IntSet.hs b/Data/IntSet.hs
index ff66b47..4f5c3dd 100644
--- a/Data/IntSet.hs
+++ b/Data/IntSet.hs
@@ -675,11 +675,11 @@ findMax (Bin _ m l r)
 
 -- | /O(min(n,W))/. Delete the minimal element.
 deleteMin :: IntSet -> IntSet
-deleteMin = maybe (error "deleteMin: empty set has no minimal element") snd . minView
+deleteMin = maybe Nil snd . minView
 
 -- | /O(min(n,W))/. Delete the maximal element.
 deleteMax :: IntSet -> IntSet
-deleteMax = maybe (error "deleteMax: empty set has no maximal element") snd . maxView
+deleteMax = maybe Nil snd . maxView
 
 {----------------------------------------------------------------------
   Map
diff --git a/tests/intmap-properties.hs b/tests/intmap-properties.hs
index 534b829..93d9eb9 100644
--- a/tests/intmap-properties.hs
+++ b/tests/intmap-properties.hs
@@ -614,10 +614,12 @@ test_findMax = findMax (fromList [(5,"a"), (3,"b")]) @?= (5,"a")
 test_deleteMin :: Assertion
 test_deleteMin = do
     deleteMin (fromList [(5,"a"), (3,"b"), (7,"c")]) @?= fromList [(5,"a"), (7,"c")]
+    deleteMin (empty :: SMap) @?= empty
 
 test_deleteMax :: Assertion
 test_deleteMax = do
     deleteMax (fromList [(5,"a"), (3,"b"), (7,"c")]) @?= fromList [(3,"b"), (5,"a")]
+    deleteMin (empty :: SMap) @?= empty
 
 test_deleteFindMin :: Assertion
 test_deleteFindMin = deleteFindMin (fromList [(5,"a"), (3,"b"), (10,"c")]) @?= ("b", fromList[(5,"a"), (10,"c")])