Syntax

lambda arg1, arg2,... argn: expression

Example

# Simple sum anonymous function definition
sum = lambda a, b, c: a + b + c;

# Call anonymous sum as a function
print("Sum of a, b, c: ", sum( 3, 4, 5 ))
print("Sum of a, b, c: ", sum( 6, 7, 8 ))

In the above example, function definition sum expects three inputs a, b, c and returns its summation. When calling sum function it appears exactly like any other python function created using def with few caveats.

• Lambdas are basically single body expressions and not true function with a statement block. They don't contain any explicit return statement rather whatever expression mentioned in lambda is computed and the value returned at the end.

• Just like def they can take multiple arguments but return just one value.

• Lambda functions creates local scope and cannot access variables other than those in their parameter list and those in the global namespace.

Just like def lambda can have default values.

sum = lambda a=3, b=2, c=1 : a + b + c;

print("Sum of a, b, c: ", sum( 7, 9, 11 ))    # prints 27

We can use lambda to generate multiplier function.

def multiplier(n):
  return lambda a : a * n

doubler = multiplier(2)
print(doubler(5))        # prints 10

tripler = multiplier(3)
print(tripler(5))        # prints 15

We can create jump tables.

L = [lambda x: x ** 2, lambda x: x ** 3, lambda x: x ** 4] 

for f in L:
    print(f(2))    # Prints 4, 8, 16

print(L[0](3))     # Prints 9