June 2018 Update

Task/Null-object/AutoIt/null-object.autoit

@@ -0,0 +1,2 @@
+Local $object = Null
+If $object = Null Then MsgBox(0, "NULL", "Object is null")

Task/Null-object/Haskell/null-object-4.hs

@@ -0,0 +1,4 @@
+add_two_maybe_numbers x y do
+  a <- x
+  b <- y
+  return (a+b)

Task/Null-object/Haskell/null-object-5.hs

@@ -0,0 +1,4 @@
+*Main> add_two_maybe_numbers (Just 2) (Just 3)
+Just 5
+*Main> add_two_maybe_numbers (Just 2) Nothing
+Nothing

Task/Null-object/Visual-Basic/null-object-1.vb

@@ -0,0 +1,15 @@
+Public Sub Main()
+Dim c As VBA.Collection
+
+' initial state: Nothing
+Debug.Assert c Is Nothing
+
+' create an instance
+Set c = New VBA.Collection
+Debug.Assert Not c Is Nothing
+
+' release the instance
+Set c = Nothing
+Debug.Assert c Is Nothing
+
+End Sub

Task/Null-object/Visual-Basic/null-object-2.vb

@@ -0,0 +1,17 @@
+Public Sub Main()
+Dim v As Variant
+
+' initial state: Empty
+Debug.Assert IsEmpty(v)
+Debug.Assert VarType(v) = vbEmpty
+
+v = 1&
+Debug.Assert VarType(v) = vbLong
+
+' assigning the Null state
+v = Null
+' checking for Null state
+Debug.Assert IsNull(v)
+Debug.Assert VarType(v) = vbNull
+
+End Sub