I am still confused about what first-class functions
are. If I understand correctly, first-class functions
should use one function as an object. Is this correct?
Is this a first-class function
?
def this_is_example(myarg1):
return myarg1
def this_is_another_ example(myarg):
return this_is_example(myarg)+myarg
this_is_another_ example(1)
A first-class function is not a particular kind of function. All functions in Python are first-class functions. To say that functions are first-class in a certain programming language means that they can be passed around and manipulated similarly to how you would pass around and manipulate other kinds of objects (like integers or strings). You can assign a function to a variable, pass it as an argument to another function, etc. The distinction is not that individual functions can be first class or not, but that entire languages may treat functions as first-class objects, or may not.
Above is an example for first class function in python.
Every function in python is first class, because they can be passed around like any other object.
"First-Class Functions" (FCF) are functions which are treated as so called "First-Class Citizens" (FCC). FCC's in a programming language are objects (using the term "objects" very freely here) which:
Actually, very roughly and simply put, FCF's are variables of the type 'function' (or variables which point to a function). You can do with them everything you can do with a 'normal' variable.
Knowing this, both
this_is_another_example(myarg)
andthis_is_example(myarg1)
are First-Class Functions, since all functions are First-Class in certain programming languages.First Class functions in Python
Properties of first class functions:
A function is an instance of the Object type.
- You can store the function in a variable. - You can pass the function as a parameter to another function. - You can return the function from a function. - You can store them in data structures such as hash tables, lists, …
Examples illustrating First Class functions in Python
1. Functions are objects: Python functions are first class objects. In the example below, we are assigning function to a variable. This assignment doesn’t call the function. It takes the function object referenced by shout and creates a second name pointing to it, yell.
Output:
HELLO
HELLO
Output:
HI, I AM CREATED BY A FUNCTION PASSED AS AN ARGUMENT.
hi, i am created by a function passed as an argument.
Output:
25
No. You are talking about higher-order functions -- refer.
First class functions: If a function can be assigned to a variable or passed as object/variable to other function, that function is called as first class function.
Python, JavaScript and C(pointers) support first class functions.
A simple example (in python):
This program is just for illustration.