- Conditional control flow is possible but currently not efficient. The current implementation will evaluate both sides of an ``if`` construct (see :func:`tensor.switch`).
- While- or for-Loops within an expression graph are not supported, but soon will be.
A ``scan`` op is in ``theano.sandbox``, but not quite ready for mainstream yet.
- While- or for-Loops within an expression graph are supported, but only via
the :func:`theano.scan` op (which puts restrictions on how the loop body can
interact with the rest of the graph).
- Neither ``goto`` nor recursion is supported or planned within expression graphs.
A few tips
----------
* Remember that your code builds a graph that theano compiles, and you cannot
literally put loops into that graph.
* Remember that Variables are symbolic of computations, not
storage. It does not make sense to *reassign* to a Variable.
