Cache function output given the same input

[yupbank]

Suppose i have a function f that takes fixed size n boolean vector as input. I'm using vmap to make it faster.
n is not very big in my setting, and i realize if i can cache the function f on top of vmap it can be much faster.
since there can only be 2^n possible unique input, when n=4, if i map this function on more than 16 rows, it's wasting computing

Is there any easy way to enable that?