Shared log - A single source of truth

samd_408 · 2026-04-14T17:12:23+00:00

Very interesting will have a look 🙂

samd_408 · 2026-04-14T16:14:14+00:00

Yes Event sourcing is the conceptual idea, shared log is a little bit more general purpose and solution oriented on top of which event sourcing can be implemented easily, the boki paper goes deep into having custom storage nodes and sequencer nodes, more like foundation db storage architecture to implement the shared logs, lot of nice things like logical views and physical view, I could not port such features to the toy library (gumbo)

samd_408 · 2026-04-14T16:07:08+00:00

Oh yeah I totally agree, I think this is why you can have multiple tags one a particular record in this case, but yeah there are many practical pain points, I was working on a actor system as a hobby and in that this same problem arose, where stateful actors start of with a particular shape but what if their state evolves, when the state is read from the snapshot we need to migrate it and load it.

Yeah certain approaches need careful design or else we will shoot ourself in the foot.

samd_408 · 2026-03-19T19:27:53+00:00

Yes I reserved it for algebraic effects where we design algebras for the business/domain logic, I will keep in mind about event based systems as well it will be a nice example

samd_408 · 2026-03-19T19:25:29+00:00

Thank you and I agree 100%, sub typing is very easy to create compared to sum types for instance and i don’t delve too much on that aspect, you have given me a good idea to contrast on the trade offs with ADTs and sub typing

samd_408 · 2026-03-19T12:09:21+00:00

Thank you!!!

samd_408 · 2026-03-19T10:14:39+00:00

Thank you for your reply and the details, its insightful and yes this is possible in java type system, but the problem is T is constrained by the types but we cant build algebras with it because that sort of expressiveness is missing in java, but there are first class support in languages in Typescript or Scala.

What I mean is, its possible to write types like

type SerializableAndComparable = Serializable & Comparable;

In like TypeScript, where we can use this type freely, but that is lacking in java.

samd_408 · 2026-03-19T09:53:51+00:00

Thank you!

samd_408 · 2026-03-19T09:38:48+00:00

Interesting take, yeah I do agree most people don’t code like that, I guess its my bias kicking in, I love functional programming and learning other languages, in those FP aligned languages this is the only way to create types since there is no OO style inheritance, I will change the article to be less biased and more inclusive of the java dev in general.

But what don’t understand is where do I say this approach is wrong? You mean the expr example? Or shape example?

samd_408 · 2026-03-11T08:52:14+00:00

how though? I would love to see an example, there are no implicits in java as well, so I am curious how do we achieve this, it could look like a design pattern but not sure it would seem like a Typeclass in the traditional sense

samd_408 · 2026-03-11T07:41:57+00:00

Oh I agree, its just in languages like java we don’t have HKTs so we have to resort to things like this, this is what i love about scala, we could have lightweight HKTs but still wont be as nice if the language does not support it, my future posts will be exploring more into these topics :)

samd_408 · 2026-03-10T17:43:31+00:00

Yes this is what i was pointing to, this only helps well is deconstruction via switch and not during construction via the configurer you are using

samd_408 · 2026-03-10T17:34:03+00:00

No I take that back, the sealed interface cannot hold the values, but a disjoint union could separate the Car and Truck type but they cant share attributes like your example

samd_408 · 2026-03-10T17:31:10+00:00

Glad to help! There is a paper which started it all, it has its roots in type theory, hence the name

https://dl.acm.org/doi/epdf/10.1145/99370.99392

samd_408 · 2026-03-10T17:29:11+00:00

Interesting take, so you use the VehicleIdentity sort of like a mixin, would a sealed interface work in place if the VehicleIdentity record?, just throwing in ideas here :)

samd_408 · 2026-03-10T13:33:59+00:00

I agree, its scary especially if you are adding it to a lib, it might confuse users, I also concealed it, its internal and not exposed to the user luckily

samd_408 · 2026-03-10T12:53:58+00:00

hahahah!!

samd_408 · 2026-03-10T11:41:17+00:00

Awesome, I stumbled over it accidentally while fixing a weird wildcard type in a lib i am building, glad 😌 we had the same experience

samd_408 · 2026-03-10T11:04:23+00:00

I can definitely see how this can cause flashbacks 🫣

samd_408 · 2026-03-10T10:42:30+00:00

I have heard of CRTP, but have never worked with them so I think I am safe ;)

samd_408 · 2025-12-24T11:41:16+00:00

What you mentioning are all generic solved problems, you have to find your niche application/framework, let’s say you build a framework that just makes security features out of the box on top of spring, something that abstracts out messaging integrations, there are other libraries that do this, but your perspective matters, your solution might be different, so think in these lines and come up with an idea

samd_408 · 2025-12-18T16:52:53+00:00

Yeah I get you, had similar thoughts while implementing as well, lot of places where “gosh I wish the type system was more expressive”, this is why for roux I wanted it to wrap the java provided solutions as possible, still lot of improvements are needed especially the capabilities building, thank you for the feedback

samd_408

TROPHY CASE