vinyl VS fgl

> Having set types like this and refining them smaller is something I wish Haskell would learn from Typescript, especially the automatic inference side

Haskell has far better type inference than Typescript in large part because it doesn't have subtyping.

There are libraries for open records and sums (e.g. https://hackage.haskell.org/package/vinyl) but they're almost always the wrong choice.

I would also like to see how this compares with data types à la carte or an extensible records solution like vinyl.

Your names are good, I reckon it is Martin Erwig's fgl stuff and Andrey Mokhov's algebraic-graphs that you have in mind.

I am about to start a new project in Haskell, model checking with (new) tree-like data structures. I think it is best to start building on a library such that i can already have elegant base functions, yet i am wondering what library is currently the standard? I read about fgl ( https://hackage.haskell.org/package/fgl ), yet it is a very old library.

Couple of approaches to graphs that are state-free: functional graphs and algebraic graphs

Using fgl but only as a data structure this time, with edge labels denoting whether the target is a big room. Not using any of its algorithms as it doesn't have anything built-in for "traversal with re-visiting".

For part 2, instead of trying to union-merge from the lowest points, I simply found all connected regions of <9. I say "simply" because I just threw things at fgl, but setting the graph up first took a bit of work. buildGr is fast but picky about the exact order things come in with.