Merge pull request #8 from terciodemelo/adds-after-range-op

Adds /drop/ syntax

Author: Zheyuan Chen

README.md

@@ -110,13 +110,17 @@ for i in 1 /to/ INF:
     print(i)
 
 print(1 /to/ INF /take/ 5)
-# there is a `take` funciton which is similar to itertools.islice
+# there is a `take` functon which is similar to itertools.islice
 # return [1, 2, 3, 4, 5]
 
 print(0 /to/ NEGINF /by/ 2 /take/ 5)
 # also works with negative infinity.
 # return [0, -2, -4, -6, -8]
 
+print(1 /to/ 10 /after/ 5)
+# there is a `after` functon which adds an offset to the range beginning
+# return [6, 7, 8, 9, 10]
+
 # print all combinations of [1..3] * [4..6]
 print([(x, y) for x, y in (1 /to/ 3) * (4 /to/ 6)])
 # return [(1, 4), (1, 5), (1, 6), (2, 4), (2, 5), (2, 6), (3, 4), (3, 5), (3, 6)]

syntax_sugar/infix.py

@@ -19,6 +19,7 @@ def __rtruediv__(self, left):
 ffilter = infix(flip(filter))
 freduce = infix(flip(reduce))
 take = infix(compose(list, islice))
+drop = infix(lambda seq, idx: islice(seq, idx, None))
 
 INF = float('inf')
 NEGINF = float('-inf')
@@ -134,4 +135,5 @@ def by(to_object, step):
     'freduce',
     'ffilter',
     'take',
+    'drop',
 ]

tests/test_infix.py

@@ -85,6 +85,11 @@ def test_infinity():
 def test_take():
     assert 1 /to/ INF /take/ 5 == [1,2,3,4,5]
 
+def test_drop():
+    assert list(1 /to/ 10 /drop/ 2 /take/ 3) == [3, 4, 5]
+    assert list(1 /to/ INF /drop/ 2 /take/ 3) == [3, 4, 5]
+    assert list(10 /to/ 1 /drop/ 3 /take/ 2) == [7, 6]
+
 def test_is_a():
     values_types_right = [
         (2, int),