Square function
Input
pow_factory(2)(3)
Output
9
pow_factory(2) returns a function that squares its input: 3**2 == 9.
Full lesson preview
Create a Configurable Power Function
Build a function factory that returns power functions with optional modular arithmetic.
Python practice15 minClosures & Function FactoriesIntermediateLast updated April 13, 2026
Problem statement
Implement pow_factory(exp, modulus=None) which returns a function that takes one argument base and returns the result of raising base to the power exp. If modulus is provided (an integer), the returned function should compute modular exponentiation using Python's built-in pow(base, exp, modulus). For non-modular mode (modulus is None) the function should return base ** exp (supporting int and float exponents). Document any type/behavior assumptions in comments.
Task
Create a pow_factory that captures exponent and optional modulus, producing functions that compute x**exp or modular exponentiation efficiently.
Examples
Input format
A call expression: pow_factory(exp, modulus)(base) or pow_factory(exp)(base).
Output format
A numeric value: int or float, or int when modulus is used.
Constraints
If modulus is provided, it must be an integer and inputs used with that returned function should be suitable for modular exponentiation (integers). For modulus=None, exponent may be int or float.
Samples
Sample 1
Input
pow_factory(0.5)(9)
Output
3.0
exp=0.5 returns square-root function; sqrt(9) == 3.0