add method reduceRight

README.md

@@ -410,7 +410,7 @@ R.propEq(1, 'v1', {'v1': 1}) # True
 - [x] reduce
 - [x] reduceBy
 - [x] reduced
-- [ ] reduceRight
+- [x] reduceRight
 - [ ] reduceWhile
 - [x] reject
 - [ ] remove

ramda/__init__.py

@@ -67,6 +67,7 @@
 from .reduce import reduce
 from .reduceBy import reduceBy
 from .reduced import reduced
+from .reduceRight import reduceRight
 from .reject import reject
 from .reverse import reverse
 from .slice import slice

ramda/reduceRight.py

@@ -0,0 +1,16 @@
+from .private._curry3 import _curry3
+from .private._helper import getAttribute
+
+
+def inner_reduceRight(fn, acc, arr):
+  idx = len(arr) - 1
+  while idx >= 0:
+    acc = fn(arr[idx], acc)
+    if acc and getAttribute(acc, '@@transducer/reduced'):
+      acc = getAttribute(acc, '@@transducer/value')
+      break
+    idx -= 1
+  return acc
+
+
+reduceRight = _curry3(inner_reduceRight)

test/test_reduceRight.py

@@ -0,0 +1,35 @@
+
+import unittest
+
+import ramda as R
+
+"""
+https://github.com/ramda/ramda/blob/master/test/reduceRight.js
+"""
+
+
+def avg(a, b): return (a + b) / 2
+
+
+def concatFirstThree(val, acc): return R.reduced(acc) if len(acc) == 3 else R.concat(acc, val)
+
+
+class TestReduceRight(unittest.TestCase):
+  def test_folds_lists_in_the_right_order(self):
+    self.assertEqual('abcd', R.reduceRight(lambda a, b: a + b, '', ['a', 'b', 'c', 'd']))
+
+  def test_folds_subtract_over_arrays_in_the_right_order(self):
+    self.assertEqual(-2, R.reduceRight(lambda a, b: a - b, 0, [1, 2, 3, 4]))
+
+  def test_folds_simple_functions_over_arrays_with_the_supplied_accumulator(self):
+    self.assertEqual(12, R.reduceRight(avg, 54, [12, 4, 10, 6]))
+
+  def test_returns_the_accumulator_for_an_empty_array(self):
+    self.assertEqual(0, R.reduceRight(avg, 0, []))
+
+  def test_short_circuits_with_reduced(self):
+    self.assertEqual('ram', R.reduceRight(concatFirstThree, '', ['a', 'd', 'm', 'a', 'r']))
+
+
+if __name__ == '__main__':
+  unittest.main()