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978 B
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Lambdas in Python
In Python, anonymous functions like arrow-functions in JavaScript (() => {})
are immediately invoked and unnamed. They are called lambdas.
Whilst they are unnamed, just like JS, the value they return can be stored in a
variable. They do not require the return keyword.
They are most often used unnamed with the functional methods map, filter and reduce.
Here is the two syntaxes side by side:
// JavaScript
const double = (x) => x * x;
# Python
double = lambda x: x * x
Here is a lambda with multiple parameters:
func = lambda x, y, z: x + y + z
print(func(2, 3, 4))
# 9
Lambdas obviously enshrine functional programming paradigms. Therefore they should be pure functions, not mutating values or issueing side effects. For example, it would be improper (though syntactically well-formed) to use a lambda to