Return List and Vector when slicing List and Vector (#96)

* Return List and Vector when slicing List and Vector

* Test

Author: chrisrink10

basilisp/lang/list.py

@@ -23,6 +23,8 @@ def __eq__(self, other):
         return self._inner == other
 
     def __getitem__(self, item):
+        if isinstance(item, slice):
+            return List(self._inner[item])
         return self._inner[item]
 
     def __hash__(self):

basilisp/lang/vector.py

@@ -23,6 +23,8 @@ def __eq__(self, other):
         return self._inner == other
 
     def __getitem__(self, item):
+        if isinstance(item, slice):
+            return Vector(self._inner[item])
         return self._inner[item]
 
     def __hash__(self):

tests/list_test.py

@@ -16,6 +16,10 @@ def test_list_seq_interface():
     assert issubclass(llist.List, lseq.Seq)
 
 
+def test_list_slice():
+    assert isinstance(llist.l(1, 2, 3)[1:], llist.List)
+
+
 def test_list_conj():
     meta = lmap.m(tag="async")
     l1 = llist.l(keyword("kw1"), meta=meta)

tests/vector_test.py

@@ -16,6 +16,10 @@ def test_vector_seqable_interface():
     assert issubclass(vector.Vector, lseq.Seqable)
 
 
+def test_vector_slice():
+    assert isinstance(vector.v(1, 2, 3)[1:], vector.Vector)
+
+
 def test_vector_conj():
     meta = lmap.m(tag="async")
     v1 = vector.v(keyword("kw1"), meta=meta)