Support mixtures defined with IfElse #76
Description
We need to add support for mixtures defined using the IfElse Op.
The following is a simple example that isn't supported:
import aesara.tensor as at
from aesara.ifelse import ifelse
from aeppl.joint_logprob import factorized_joint_logprob
srng = at.random.RandomStream(seed=2320)
I_rv = srng.bernoulli(0.5, name="I")
X_rv = srng.normal(0, 1, name="X")
Y_rv = srng.gamma(0.5, 0.5, name="Y")
Z_rv = ifelse(I_rv, X_rv, Y_rv)
Z_rv.name = "Z"
z_vv = Z_rv.clone()
i_vv = I_rv.clone()
logp_parts = factorized_joint_logprob({Z_rv: z_vv, I_rv: i_vv})