TensorFlow implemented Poisson sampling in the TensorFlow r1.1 pre-release (you can install it via
pip install --pre tensorflow). This is the most immediate solution. That said, TensorFlow r1.1 made major backwards incompatible changes to distributions, such as a move from greek arguments to english-based arguments. For example, it is now
Poisson(rate=tf.exp(eta)) and not
lam=. To use TensorFlow r1.1 with Edward, see https://github.com/blei-lab/edward/pull/452.
If you prefer not to use a development version of TensorFlow and Edward, there are two other options, described in the Advanced Settings section of http://edwardlib.org/api/model-development. One is to implement your own Poisson sampling. The other option is if you only use the Poisson as a likelihood function (and you use inference algs that don't require sampling from the likelihood); then use the
value argument to fix the associated tensor to some value.