Tensor Considered Harmful Part 2
A couple critiques for this article’s argumentative approach, as well as the proposed library. My expertise is not in Torch, but I believe these thoughts are valid on a more general level.<p>Yes, the ability to add names to dimensions of Tensor objects would be useful. Accessing components by named dimension instead of numeric indices (assuming clean syntax) would reduce mental overload for both readers and writers of code. However, the examples provided do a poor job of making the case that people should use this library. I’ll try breaking the issues down into these buckets:<p>* Awkward UX<p>* Muddied and uninteresting examples<p>* Missing the point<p>---<p>Awkward UX<p>First and foremost, it’s hard to ignore that this API is not fully fleshed out. I appreciate that the author is explicitly seeking feedback and taking an iterative approach, but it feels like there needed to be some more time spent thinking about how to best approach fixing the problem at hand from a user perspective.<p>Since this post explicitly attempts to take a pragmatic approach, it’s important to understand that pragmatic users will only tolerate as much user-unfriendliness in a library as it provides value. Idealistic users will happily saddle themselves with difficult&#x2F;painful libraries, but pragmatic users demand value for pain. And unfortunately, while it is useful to have named dimensions in a Tensor, it is not so useful that a user should be expected to completely shift the way they write their code. This library asks above-and-beyond what I’d expect a client to reasonably sign up for. A couple examples:<p>* Forcing users to use a vaguely named op() method to wrap functions, but only sometimes (for functions that “change dimensions”?).
* Wrapping Torch library functions, but changing their signature along the way (e.g. the sample() method for distributions)
* Incompatibility between NamedTensor and base Tensor with raw Torch (ie. if a client uses NamedTensor, they don’t get to use the rest of the Torch ecosystem as-is without manual access to the underlying Tensor object).<p>Note that I’m not making note about some of the controversial decisions here (such as not allowing for explicit dimension access by index). There’s discussion to be made there, too, but I want to focus on the decisions that were made implicitly, as that’s where many UX issues can arise.<p>The author seems open to taking advice and iterating from there. My recommendation would be to iterate the API even earlier: _before_ writing implementation code. It will be faster to type out some example client uses and see what people think than to implement a working version and find out it fails in some cases. You’ll also find it easier to take a step back, as you won’t have spent as much time in the code you’ve already written. This may allow for a fresh perspective on what would make the most useful&#x2F;useable API.<p>---<p>Muddied and uninteresting examples<p>Several of the examples given make it hard to compare the original version of the code and the proposed version. This is most obvious in the MNIST example. The default version uses a “reassign to same variable” approach, while the proposed version uses method-chaining. Some of this may be due to some of the issues mentioned above, but I want to note that it detracts from the author’s argument as it distracts a reader who many otherwise be on board.<p>The examples given aren’t particularly inspiring, either. The “Experiments on Canonical Models” section includes toy examples, many of which are just as readable (if not more so) in the original format as they are in the NamedTensor version.<p>---<p>Missing the point<p>At the end of the day, there’s a large stack of reasons why working on adding named dimensions to Tensors is useful. After the first article came out, it seems that the author received a fair amount of comment on how pragmatic their proposed approach was. Unfortunately, I feel like the author took “pragmatic” to mean “how would one literally use the library as it stands” as opposed to a challenge to consider the practicalities of the end-user and the tradeoffs that need to be made between the ideals of the author and the needs of the client.<p>I think the main failing of this library&#x2F;article is that instead of honing in on a narrow-scoped thesis of “how Tensors should have their dimensions named”, it ends up being distracted by the quirks of the way the named tensor library was implemented. I think the author may benefit from taking a step back from what they have and thinking about how they could achieve their goals in a more cohesive way.