Expression vs Statement in lambdas

Question

I never understood the quiz question
"lambdas can have no statement" .
What else do they have?
I guess expressions but whats the difference and why do we have this constraint?

Answer 1

Lambdas can have no statements

Lambdas cannot have if and else statements or loops (there a lot more statements!)

Lambdas are just like

def name(arguments):
return """body of lambda"""

But you can have ternary operators and list comprehension and warlus operators.

ternary operator:

value_if_true if Boolean else value_if_false

List comprehension :

[i for i in range(3)] # [0, 1, 2]

Warlus operator:

(x := 5) # returns x and x is a variable now

Research more on those operators.

But for why we have this limitation is because there's no difference between a lambda and a function in python so why not make a function, and it will probably be controversial for example the warlus operator was so controversial that Guido Van Rossum (creator of python) resigned as BDFL

Answer 2

Hima , your comment, what lambda can't have, seems to be not correct.

- return, pass, assert, raise -> can not be used
- expressions are possible. see sample of some valid lamdbas
- y = x*2 is an assignment with an expression. These can not be used in lambdas

here some samples of valid lambdas:

map_ = list(map(lambda x: x*2, list_))
result = list(filter(lambda x: (x % 2 == 1) and (x >= 10), fib))
print(reduce(lambda x,y:x*y,range(1,n+1)))
res = sorted(A,key=lambda x : x[2].lower())

Answer 3

Lothar
That was just to show a difference between expression and statement .
I never said lambdas can have statements .
I should have put it in a better way .
👍

Answer 4

a lambda can't have these:
return
pass
assert
raise
x**2 # an expression
y=x**2 # a statement

Answer 5

Oma Falk
expressions :
a*b+c
max(a,b,c)
"aa"+"aa"

statements :
def fun()
return something
try :
something
If clause:
something

Answer 6

Hima can u give me
3 statement examples
and
3 expression examples please ?

Answer 7

Oma Falk

B enevolent
D ictator
F or
L ife

Just means he decides if the pep (Python Enhancement Proposal) will be done or not.

Answer 8

Expressions refer to anything that can be evaluated to produce a value. An Expression must return a value.

Statements do not return a value. They perform an action, and evaluate nothing. Statements may contain expressions, which must be evaluated. But the statement itself is not evaluated.

Examples for expressions:
1
4*3
„Hello World“
„Hello“ + „ World“
False

Examples for statements:
return
x = 17
if x:
print()

Answer 9

BDFL?

Answer 10

print() is an expression. Just because it has a side effect doesnt mean it's not an expression. It still returns None

Answer 11

Zachiah sawyer You are right, „print“ was a statement in Python 2, but since Python 3 it is a function.

Answer 12

from __future__ import print_function
Lol

Answer 13

Hello,

A lambda expression is a syntax that allows you to create a function without name directly inside your code, as an expression.

There are two kinds of lambda expressions, depending on their body:

expression lambdas, whose body is just an expression, e.g. (i, j) => i + j
statement lambdas, whose body is a full statement, e.g.. (i, j) => { return i + j; }

i hope this will help to you..