Theano scan over tensor.

error

Failed to infer_shape from Op Subtensor{1:9223372036854775807:}.
Input shapes:[(Elemwise{add,no_inplace}.0, Subtensor{1}.0)]
Exception encountered during infer_shape: <type 'exceptions.AssertionError'>
Exception message: 
Traceback: Traceback (most recent call last):
  File "/Users/bayerj/devel/third-party/Theano/theano/tensor/opt.py", line 721, in on_import
    o_shapes = shape_infer(node, [self.shape_of[r] for r in node.inputs])
  File "/Users/bayerj/devel/third-party/Theano/theano/tensor/basic.py", line 2863, in infer_shape
    assert len(xshp) == node.inputs[0].ndim
AssertionError

Failed to infer_shape from Op Subtensor{int64:int64:int8}.
Input shapes:[(Elemwise{add,no_inplace}.0, Subtensor{1}.0), None, None, None]
Exception encountered during infer_shape: <type 'exceptions.AssertionError'>
Exception message: 
Traceback: Traceback (most recent call last):
  File "/Users/bayerj/devel/third-party/Theano/theano/tensor/opt.py", line 721, in on_import
    o_shapes = shape_infer(node, [self.shape_of[r] for r in node.inputs])
  File "/Users/bayerj/devel/third-party/Theano/theano/tensor/basic.py", line 2863, in infer_shape
    assert len(xshp) == node.inputs[0].ndim
AssertionError

Traceback (most recent call last):
  File "test.py", line 26, in <module>
    print f(X)
  File "/Users/bayerj/devel/third-party/Theano/theano/compile/function_module.py", line 596, in __call__
    self.fn()
  File "/Users/bayerj/devel/third-party/Theano/theano/gof/link.py", line 288, in streamline_default_f
    raise_with_op(node)
  File "/Users/bayerj/devel/third-party/Theano/theano/gof/link.py", line 284, in streamline_default_f
    thunk()
  File "/Users/bayerj/devel/third-party/Theano/theano/gof/cc.py", line 1217, in thunk
    return p(n, [x[0] for x in i], o)
  File "/Users/bayerj/devel/third-party/Theano/theano/scan_module/scan_op.py", line 530, in perform
    outs[j][0][pos[j]] = output_storage[offset_out+j].storage[0]
ValueError: ('output operand requires a reduction, but reduction is not enabled', scan_fn{inplace,cpu}(Elemwise{Composite{sub,minimum}}[(0, 2)].0, tensordot.0, InplaceSetIncSubtensor{:int64:}.0), 'Sequence id of Apply node=22')

gistfile1.txt

import scipy
import theano
import theano.tensor as T

insize = 2
hiddensize = 3
outsize = 2

inweights = T.shared(scipy.empty((2, 3)))
hidden0 = T.shared(scipy.empty(3))

inpts = T.tensor3('input-sequences')
hidden = T.tensordot(inpts, inweights, axes=([2], [0]))
hidden_rec, _ = theano.scan(
  lambda x, h_tm1: x + 1,
  sequences=hidden,
  outputs_info=[hidden0])
    
f = theano.function([inpts], hidden_rec)

X = scipy.array([
  [[2, 3], [1, 2], [-1, 1]],
  [[1, 0], [0, 1], [1, 2]],
])

print f(X)