Would love to see your solution for one of these problems!
-- ((start, end), heightMap)
type Input = ((Coordinate, Coordinate), BoundedHeightMap)
-- (length remaining, next coordinate)
type DirectionsMap = M.Map Coordinate (Int, Coordinate)
https://github.com/cronin101/AdventOfCode/blob/master/2022/D...
Day 13 on the other hand is something I'm far less ashamed of and really lets Haskell shine, it basically didn't need any code at all. I just defined how to parse an equivalent data representation, how it was sorted via Eq/Ord typeclass (following the brief), and used `compare` to do the lifting.
instance Eq PacketData where
(L l) == (P p) = P [L l] == P p
(P p) == (L l) = L l == P p
P p == P p' = p == p'
L l == L l' = l == l'
instance Ord PacketData where
compare (L l) (P p) = compare (P [L l]) (P p)
compare (P p) (L l) = compare (P p) (P [L l])
compare (P p) (P p') = compare p p'
compare (L l) (L l') = compare l l'
For me the parsing was the hardest part when trying without mutable state so this helps a lot.
I'll admit first few times were a bit of a headache learning the library (https://hackage.haskell.org/package/attoparsec-0.14.4/docs/D...) and idiomatic patterns, plus how to test/troubleshoot. But now Haskell is my go-to language for parsing and I can parse pretty much any AoC input into a suitable representation, with the forethought taking no longer than reading the brief, by composing parsers for the different parts of the input string into a larger parser.
Also, disclaimer, since I'm the only one reading my code I often make oneliner "pointfree" parsers using dense syntax/tricks (as a little extra mental puzzle) instead of vastly more readable "do notation", so don't let the special character soup put you off.