There might not be…
So there are three equivalent representations here with different types:


List[Tensor] a list of sequences.

Tensor a single tensor of sequences with padding. Crucial extra information: pad value, whether it is seq first or batch first.

PackedSequence an object containing packed sequences. Contains the extra informaiton: batch sizes, indices from reordering.

So then the conversion functions all go between them, and you can just go by the type signatures to see which is appropriate: pad_sequence: 1 → 2  pad_packed_sequence 3 → 2 , pack_padded_sequence 2 → 3, pack_sequence 1 → 3.