Python3-Functional programming

function-type programming

Functional programming is a kind of programming method, it treats the computer operation as the function computation; In layman's terms, a mathematical logic is used to define an expression, and then a function is used to implement this function.

Example (python3.0+):

y = 2*x+1  ----first define a mathematical expression def cal (x): "' Description: function to implement the above expression" ' return 2*x+1# the above procedure is functional programming

How can I tell if a function is functional programming?

• Do not use variables to save state (do not assign values to variables), do not modify variables

Example (python3.0+):

# Non-functional Programming n = 1def cal ():    global n    n+=1    return n cal () # Functional Programming n =1 def CAL (N):    return n+1cal (10)

function is variable

In Python programming, there is a saying: function is variable, how to embody it?

Example (python3.0+):

def foo (n):p rint (n) def Bar (name):    print (' My name is Sunwk ')    foo (bar) # treats the function bar (that is, the memory address of the bar function) as a variable (parameter) Passed to the Foo function result:>>> <function bar at 0x0000000000fa58c8>

Higher order functions

With know more knowledge, contact surface wide, also more and more confused, just began to contact higher-order functions, what is the advanced function Ah, first a few examples to see it

Example (python3.0+):

def foo ():    print (' from foo ') def Bar ():    print (' from bar ')    return FOOA = Bar () print (A ()) # Run result:>>> From Bar>>>from foo>>>none "" "Why did you finally output a None, because print (a ()), first executes a () relative to execute foo (), but after print, the equivalent of output foo ( Return value is not defined in the Foo function, so return none "" "

Summary of higher-order function characteristics:

1. The parameter received by the function is a functional name
2. The return value contains the function

Python3-Functional programming