#!/usr/bin/python3
# -*- coding: utf-8 -*-

# %% Lambda functions
"""
These are tiny instantly executable functions,
that are often defined in-place, as arguments to other functions.

General format
    lambda argumentss: expression on arguments

It must be one expression (line)

It can't do arg type-hints in the function def itself, 
but can type-hint a the variable itself that stores a lambda.
However, you usually wouldn't do that anyway...
"""

from typing import Callable


# This is equivalent to below
def add_one(x: int) -> int:
    return x + 1


print(add_one(2))

# to this
plus_one: Callable[[int], int] = lambda x: x + 1
print(plus_one(2))

# and to this instantly evaluated lamda
print((lambda x: x + 1)(2))


# This second function is equivalent to below
def xplusyadd_one(x: int, y: int) -> int:
    return x + y + 1


print(xplusyadd_one(2, 2))

# to this
xplusyplus_one: Callable[[int, int], int] = lambda x, y: x + y + 1
print(xplusyplus_one(2, 2))

# and to this
print((lambda x, y: x + y + 1)(2, 2))

# Some more examples called upon definition:
print((lambda x: x > 2)(3))
# => True
print((lambda x, y: x ** 2 + y ** 2)(2, 1))
# => 5

# %% Lambda sum example
mysum: Callable[[int, int], int] = lambda arg1, arg2: arg1 + arg2
# Now you can call sum as a function
print("Value of total: ", mysum(10, 20))
print("Value of total: ", mysum(20, 20))


print((lambda: print("can have zero args"))())

# ++++++++++++ Cahoot-20.1
# https://mst.instructure.com/courses/58101/quizzes/57315