understanding_lambdas.py

"""
  Python's lambda is an alternative way to create a function,
  something like anonymous functions in pl/sql, and javascript.
"""


def input_times_whatever(n):
    return lambda a: a * n 


input_times_1 = input_times_whatever(1)
input_times_2 = input_times_whatever(2)
input_times_3 = input_times_whatever(3)


# print 12 several times
for twelve in [ 
    input_times_1(12),
    input_times_3(4),
    input_times_whatever(2)(6),
    map(lambda a: int(a * 0.5), [24, input_times_1(24), input_times_2(12)]),
]:
    if not isinstance(twelve, map):
        print("direct: {}".format(twelve))
    else:
        for t in twelve:
            print("mapped: {}".format(t))

list_0_to_5 = ["zero", "one", "two", "three", "four", "five"]
list_int_each = list(range(len(list_0_to_5)))
list_int_even = [0, 2, 4]
                                                                                                                                                                                                                   
if list_int_even == [b for b in filter(lambda x: x % 2 == 0, list_int_each)]:
    print("x % 2 == 0 -> even numbers")

dict_0_to_5 = {k: v for v, k in enumerate(list_0_to_5)}
print([r for r in filter(lambda i: i in ["one", "four"], dict_0_to_5)])