Summing param values

Not sure if I should be asking here or on one of Jax's other package pages, but is there an easy way of summing param values? Eg if I have two Params-type variables a and b of the same structure, how could I do:
a = a * alpha + (1 - alpha) * b
to update a's values by taking elementwise linear combinations of a and b's values? I am not planning on updating a via gradient descent at all, so I think it's fine if the method of doing this doesn't preserve differentiability.