[larve]

that's interestingly enough not something I'm interested in (formally deriving things and doing "proper" maths as part of my software work). I care much more about developing new intuitions, and seeing the category theoretical definition of monoid https://en.wikipedia.org/wiki/Monoid_(category_theory) inspired me a lot.

In fact I think that one of the great things about software is that you can not care about being very formal, and you can just bruteforce your way through a lot of things. DO your database calls really compose? or can pgbouncer throw some nonsense in there? Well maybe it breaks the abstraction, but we can just not care and put in a cloudformation alert in there and move on.

[layer8]

> seeing the category theoretical definition of monoid https://en.wikipedia.org/wiki/Monoid_(category_theory) inspired me a lot.

What applicable insight did you gain over the normal algebraic definition (https://en.wikipedia.org/wiki/Monoid)?

[larve]

Mostly confirm that drawing things as boxes and arrows even though I implement them as folds/monoids (state machines, binary protocol decoders) and implementing the comonoid by "reversing the arrows" (to do log reconstruction when debugging) has a name, and thus is a fruitful practice for me to continue doing, instead of it being "those weird drawings I keep noodling".

Nothing is rocket science, and you can totally get there without even the traditional monoid definition, but seeing the same diagrams I kept drawing before porting something to more "traditional" code patterns was quite validating.

completely rough whatever that tries to match stuff I did on a ps2 protocol decoder a while ago. Being able to invert state machines that use time ticks to advance requires adding additional counters to make them work properly, iirc. As you can tell none of this is formal, in fact I worked on this before starting my CT joint, but you can maybe see why I resonate more with the CT formulation of things.

The bigger picture here is that when I do embedded dev, I only have so much memory to keep an event log, so I need to be able to work backwards from my last none state, instead of traditionally walking forward from an initial state and incoming events. That this whole concept of "swapping the arrows around" is something that reputable people actually study was super inspiring.

https://media.hachyderm.io/media_attachments/files/109/434/7...