add method assoc

README.md

@@ -82,7 +82,10 @@ R.add(date(1,2,3), date(1,2,3)) # float('nan)
 - [ ] applySpec
 - [ ] applyTo
 - [ ] ascend
-- [ ] assoc
+- [x] assoc
+
+Currently, we only support list and dict type.
+
 - [x] assocPath
 
 Currently, we only support list and dict type.

ramda/__init__.py

@@ -8,6 +8,7 @@
 from .ap import ap
 from .append import append
 from .apply import apply
+from .assoc import assoc
 from .assocPath import assocPath
 from .binary import binary
 from .chain import chain

ramda/assoc.py

@@ -0,0 +1,4 @@
+from .assocPath import assocPath
+from .private._curry3 import _curry3
+
+assoc = _curry3(lambda prop, val, obj: assocPath([prop], val, obj))

test/test_assoc.py

@@ -0,0 +1,54 @@
+
+import unittest
+
+import ramda as R
+
+"""
+https://github.com/ramda/ramda/blob/master/test/assoc.js
+"""
+
+
+class TestAssoc(unittest.TestCase):
+  def test_makes_a_shallow_clone_of_an_object_overriding_only_the_specific_property(self):
+    obj1 = {'a': 1, 'b': {'c': 2, 'd': 3}, 'e': 4, 'f': 5}
+    obj2 = R.assoc('e', {'x': 42}, obj1)
+    self.assertEqual({'a': 1, 'b': {'c': 2, 'd': 3}, 'e': {'x': 42}, 'f': 5}, obj2)
+
+    self.assertEqual(obj1['a'], obj2['a'])
+    self.assertEqual(obj1['b'], obj2['b'])
+    self.assertEqual(obj1['f'], obj2['f'])
+
+  def test_is_the_equivalent_of_clone_and_set_if_the_property_is_not_on_the_original(self):
+    obj1 = {'a': 1, 'b': {'c': 2, 'd': 3}, 'e': 4, 'f': 5}
+    obj2 = R.assoc('z', {'x': 42}, obj1)
+    self.assertEqual({'a': 1, 'b': {'c': 2, 'd': 3}, 'e': 4, 'f': 5, 'z': {'x': 42}}, obj2)
+
+    self.assertEqual(obj1['a'], obj2['a'])
+    self.assertEqual(obj1['b'], obj2['b'])
+    self.assertEqual(obj1['f'], obj2['f'])
+
+  def test_makes_a_shallow_clone_of_an_array_overriding_only_the_specific_index(self):
+    newValue = [4, 2]
+    arr1 = [1, [2, 3], 4, 5]
+    arr2 = R.assoc(2, newValue, arr1)
+    self.assertEqual([1, [2, 3], [4, 2], 5], arr2)
+
+    self.assertEqual(arr1[0], arr2[0])
+    self.assertEqual(arr1[1], arr2[1])
+    self.assertEqual(newValue, arr2[2])
+    self.assertEqual(arr1[3], arr2[3])
+
+  def test_is_the_equivalent_of_clone_and_set_if_the_index_is_not_on_the_original(self):
+    newValue = [4, 2]
+    arr1 = [1, [2, 3], 4]
+    arr2 = R.assoc(5, newValue, arr1)
+    self.assertEqual([1, [2, 3], 4, None, None, [4, 2]], arr2)
+
+    self.assertEqual(arr1[0], arr2[0])
+    self.assertEqual(arr1[1], arr2[1])
+    self.assertEqual(arr1[2], arr2[2])
+    self.assertEqual(newValue, arr2[5])
+
+
+if __name__ == '__main__':
+  unittest.main()