Merge pull request #13 from adrian17/master

implemented last_option

README.md

@@ -69,7 +69,10 @@ seq([1, 2, 3])[-1]
 
 ## List of supported functions
 ### List to List
+* init: get everything except last element
 * tail: get everything except first element
+* inits: get subsequent inits
+* tails: get subsequent tails
 * drop: drop first n elements
 * drop_while: drop first elements using f
 * take: take first n elements
@@ -96,6 +99,7 @@ seq([1, 2, 3])[-1]
 * head, first: get first element
 * head_option: get first element or None
 * last: get last element
+* last_option: get last element or None
 * reduce: reduce sequence using f
 * fold_left
 * fold_right

functional/chain.py

@@ -127,6 +127,20 @@ def last(self):
         """
         return _wrap(self.sequence[-1])
 
+    def last_option(self):
+        """
+        Returns the last element of the sequence or None, if the sequence is empty.
+
+        >>> seq([1, 2, 3]).last_option()
+        3
+
+        >>> seq([]).last_option()
+        None
+        """
+        if not self.sequence:
+            return None
+        return self.last()
+
     def init(self):
         """
         Returns the sequence, without its last element.

test/test_functional.py

@@ -120,6 +120,15 @@ def test_last(self):
         self.assertEqual(l.last(), [3, 4])
         self.assertType(l.last())
 
+    def test_last_option(self):
+        l = seq([1, 2, 3])
+        self.assertEqual(l.last_option(), 3)
+        l = seq([1, 2, [3, 4]])
+        self.assertEqual(l.last_option(), [3, 4])
+        self.assertType(l.last_option())
+        l = seq([])
+        self.assertIsNone(l.last_option())
+
     def test_init(self):
         l = seq([1, 2, 3, 4])
         expect = [1, 2, 3]