Python Learning 4 Functional Programming (Liaoche)

First, higher order function

1. Variables can point to functions

For example, Python's built-in absolute value function abs ():

f=ABSprint(f (-10))

The output is 10.

2, function name is also variable

Any function name is a variable, and if it is assigned, it can no longer be used for function calls:

abs=10Print(ABS ( -8))    #abs points to 10, can no longer use ABS () to call the function, will error

Note: Because the abs function is actually defined in import builtins the module, so to make abs the change of the pointer in the other module also takes effect, to use the import builtins; builtins.abs = ten .

3. Incoming function

A function can receive another function as a parameter, and this function is called a higher order function. For example:

def Add (x, Y, f):     return f (x) + f (y) a=add ( -5,6, ABS)print(a)

Output is 11

Second, Map/reduce

Python Learning 4 Functional Programming (Liaoche)