"""
Module with functions that demonstrate closures and currying.

"""


def uppercase_my_str(s, n):
    if n == 0:
        return s[0].upper() + s[1:]

    return s[:n] + s[n].upper() + s[n + 1:]


# curried form
def uppercase_at(n):
    def uppercase_my_str(s):
        if n == 0:
            return s[0].upper() + s[1:]

        return s[:n] + s[n].upper() + s[n + 1 :]

    return uppercase_my_str


ys = ["hello", "world"]

# returns a closure in which n = 0 (so uppers first letter)
upper_at_1st_letter = uppercase_at(0)
print(list(map(upper_at_1st_letter, ys)))

# shorter notation
print(list(map(uppercase_at(0), ys)))

# using lambda
print(list(map(lambda s: uppercase_at(0)(s), ys)))