add method lift

README.md

@@ -443,7 +443,7 @@ R.length(ObjWithoutLength()) # float('nan')
 - [ ] lensIndex
 - [ ] lensPath
 - [ ] lensProp
-- [ ] lift
+- [x] lift
 - [x] liftN
 - [x] 0.1.2 lt
 - [x] 0.1.2 lte

ramda/__init__.py

@@ -60,6 +60,7 @@
 from .last import last
 from .lastIndexOf import lastIndexOf
 from .length import length
+from .lift import lift
 from .liftN import liftN
 from .lt import lt
 from .lte import lte

ramda/lift.py

@@ -0,0 +1,5 @@
+from .liftN import liftN
+from .private._curry1 import _curry1
+from .private._inspect import funcArgsLength
+
+lift = _curry1(lambda fn: liftN(funcArgsLength(fn), fn))

test/test_lift.py

@@ -0,0 +1,42 @@
+
+import unittest
+
+import ramda as R
+from ramda.private._isFunction import _isFunction
+
+from .helpers.Maybe import Just
+
+"""
+https://github.com/ramda/ramda/blob/master/test/lift.js
+"""
+
+add3 = R.curry(lambda a, b, c: a + b + c)
+add4 = R.curry(lambda a, b, c, d: a + b + c + d)
+add5 = R.curry(lambda a, b, c, d, e: a + b + c + d + e)
+complement = R.lift(R.Not)
+madd3 = R.lift(add3)
+madd4 = R.lift(add4)
+madd5 = R.lift(add5)
+
+
+class TestLift(unittest.TestCase):
+  def test_returns_a_function_if_called_with_just_a_function(self):
+    self.assertEqual(True, _isFunction(R.lift(R.add)))
+
+  def test_produces_a_cross_product_of_array_values(self):
+    self.assertEqual([3, 4, 5, 4, 5, 6, 4, 5, 6, 5, 6, 7, 5, 6, 7, 6, 7, 8], madd3([1, 2, 3], [1, 2], [1, 2, 3]))
+    self.assertEqual([6], madd3([1], [2], [3]))
+    self.assertEqual([9, 10, 10, 11, 10, 11, 11, 12], madd3([1, 2], [3, 4], [5, 6]))
+
+  def test_can_lift_functions_of_any_arity(self):
+    self.assertEqual(False, complement(R.isNil)(None))
+    self.assertEqual([6, 15], madd3([1, 10], [2], [3]))
+    self.assertEqual([46, 55], madd4([1, 10], [2], [3], [40]))
+    self.assertEqual([546, 1046, 555, 1055], madd5([1, 10], [2], [3], [40], [500, 1000]))
+
+  def test_works_with_other_functors_such_as_maybe(self):
+    addM = R.lift(R.add)
+    self.assertEqual(True, R.equals(Just(8), addM(Just(3), Just(5))))
+
+if __name__ == '__main__':
+  unittest.main()