Comment by Jeaye
2 days ago
I agree with you, but perhaps in my own way. Jumping into an arbitrary Clojure program can be tough, since the data shapes may not be defined anywhere. Hopefully the program uses spec or malli, but even then, unless they annotate every function with the shape it expects, you may be left needing to REPL in and poke around. However, REPLing in to check just a function or two may not be easy if the program requires some setup and doesn't use integrant or similar.
Once Clojure parity is achieved, I'm interested in static typing, pattern matching, value-based errors, and some other opt-in improvements that I think will greatly improve both readability and toolability (i.e. how well tooling can work with the code, based on what it knows of the code). Stay tuned. :)
What’s your take on Hickey’s talk titled “Maybe Not” which fundamentally criticizes static types? Is there a middle ground where some form of static typing makes sense in a Clojure-esque world?
https://youtu.be/YR5WdGrpoug?si=4mI8doBX6jj6PJkk
Rich has many great ideas and he founded Clojure. I respect him deeply. On typing, however, we do not agree entirely.
For a practical example of a Clojure-like language with a completely static type system (with affine typing), see Carp. https://github.com/carp-lang/Carp
I don't see why there can't be a Carp mode in jank, with bridges in place to connect the Clojurey world from the Carpy world. This would allow jank users to develop interactively to start with, figure out their shapes, use the REPL, etc. Then, if they want, they can lock down some parts of the code for both performance and correctness gains.
FWIW, (I have one Clojure project I inherited at work that my team maintains) I love this direction.
Heh. Hickey once debated with me at length about visual neuroscience, a subject I have a master's degree in and he doesn't. At no point did this stop him from confidently asserting things.
I have to wonder if "Maybe Not" is similar, since he's not actually an expert in types, either afaik.
Alexis King wrote a partial rebuttal to Maybe Not: https://lexi-lambda.github.io/blog/2020/01/19/no-dynamic-typ...
This "rebuttal" is a mix of subtle ad hominem attacks and strawman arguments. Not recommended.
I'd personally say typing or not is a style choice, but your criticism here seems to be that Hickey doesn't have a visual neuroscience Master's degree which seems a bit arbitrary.
If your argument is you are an expert but Hickey is not, criticising him on his language design skills seems like a logical mistake. He's one of the foremost language designers of the current era. "Maybe Not" is a speech by an expert talking in his field of expertise.
If your argument is that his confidence is unfounded, again, he's an expert talking in his area. He can reasonably take a confident attitude in that, even if he has unfounded confidence in other fields he isn't an expert in. Lots of experts do that, it is a well founded stereotype of smart people.
He doesn't need to be an expert in implementing types to judge whether they are a good language feature.
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Been a while since I've watched/read it, but I remember the ideas in Maybe Not being quite interesting.
To me, the really important idea wasn't a criticism of static types in general.
Instead it was the idea that static typing in most (all?) mainstream implementations conflates concepts that should be separate, specifically the shape of the information that we have (e.g. what fields of what types), and whether a particular bit of information is available and required (e.g. nullability).
He contends that the former belongs in our usual "type definition", whereas the latter relates instead to a given context. For example, my PassportForm type always has a date-of-birth field in its _shape_, but whether it's statically required/present to exist depends on whether we're at a HTTP API boundary, an internal domain function boundary, writing into a database.
It sounded like that kind of "nullability masking" was intended as a feature of Spec, but I don't get the impression it was ever implemented.
I don’t think Rich was criticizing static types as much as saying that they aren’t giving you as much benefit as you think they are and that they complicate program evolution over time.
They might not give much execution benefit and they may indeed complicate program evolution, but they DO aid readability, document-ability and refactoring!
I don't think static types (or lack thereof) complicate (or simplify) program evolution over time, bad architecture does.
Still quite the hot take.
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If you need confidence in the operation of a function you make code testable. If you need it to execute in Repl you need to make code Replable and I am not joking.
If you can run it, then you can REPL it, no matter how deeply nested. Scope-capture (https://github.com/vvvvalvalval/scope-capture) has been probably the most important tool in my box. Hope jank supports it eventually.
Thanks for jank! It’s great to be reading about it, listening to you talking about it at conferences, and I can’t wait to try it out!
> pattern matching, value-based errors
I did not know these were in the cards, that makes jank even more exciting!
Core spec is enough. Types do not tell the truth. Contracts do the data type casting and data testing. A ubiquitous combo in data engineering.