gistfile1.py

W = T.matrix('weights')
initial = T.vector('initial')
inpt = T.matrix('inpt')

def one_step(x_t, h_tm1, W):
  expr = dot(h_tm1, W) + x_t
  return expr

expr, _ = theano.scan(
  fn=one_step,
  sequences=[inpt],
  outputs_info=[initial],
  non_sequences=[W])

sh = expr.shape[0]
shapef = theano.function([W], sh,
                         givens={initial: theano.shared(scipy.ones(5)),
                                 inpt: theano.shared(scipy.ones((5, 5)))})
print shapef(scipy.ones((5, 5)))


cost = expr.sum()
f = theano.function([W], cost,
                    givens={initial: theano.shared(scipy.ones(5)),
                            inpt: theano.shared(scipy.ones((5, 5)))})

print f(scipy.ones((5, 5)))
f2 = theano.function([W, inpt], cost,
                     givens={initial: scipy.zeros(5)})

print f2(scipy.ones((5, 5)), scipy.ones((10, 5)))