After attempting to implement seq2seq with packed_sequences, I have come to the conclusion that this is not really feasable as,


seq2seq requires last hidden/cell state for each element in batch.  I believe there is no API call to do this when using packed, sequences.


The way packed sequences work at the moment, is that they require inputs to be sorted by length.  As OP points out, this requires a mirrored re-ordering of the target inputs.


It appears to me that fundamentally, packed sequences require a lot of fenangling to work as currently implemented.  It feels like they could benefit from a little more abstraction to make things a bit easier for the programmer.
Happy to be corrected/proven wrong here!