# Partial functions in Python

What if you could define an abstract function and specialize it in order to create diﬀerent versions of it? Thinks it as a sort of function Inheritance where you bind specific params to make them reliable for a specific scenario. Partial functions in Python perform this function easily.

## Param details

``the number to be raised``

ythe exponent

raise the function to be specialized

As you probably know if you came from OOP school, specializing an abstract class and use it is a practice you should keep in mind when writing your code.

What if you could define an abstract function and specialize it in order to create diﬀerent versions of it? Thinks it as a sort of function Inheritance where you bind specific params to make them reliable for a specific scenario. Partial functions in Python performs this function easily.

## Partial functions in Python: Raise the power

Let’s suppose we want raise x to a number y.

You’d write this as:

`def raise_power(x, y):return x**y`

What if your y value can assume a finite set of values?

Let’s suppose y can be one of [3,4,5] and let’s say you don’t want oﬀer end user the possibility to use such function since it is very computationally intensive. In fact you would check if provided y assumes a valid value and rewrite your function as:

`def raise(x, y):if y in (3,4,5):return x**yraise NumberNotInRangeException("You should provide a valid exponent")`

Messy? Let’s use the abstract form and specialize it to all three cases: let’s implement them partially.

`from functors import partialraise_to_three = partial(raise, y=3)raise_to_four = partial(raise, y=4)raise_to_five = partial(raise, y=5)`

What happens here? We fixed the y params and we defined three diﬀerent functions.

No need to use the abstract function defined above (you could make it private) but you could use partial applied functions to deal with raising a number to a fixed value.

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