for those aha! moments

https://github.com/arianvp/crdt/blob/3cad584da0a89623d061bc9cf9f7bf8e23b6c1c5/src/CRDT/IncrementOnlyCounter.hs#L35

• Map.insertWith

-- | Increments the counter
increment :: Ord a => a -> IncrementOnlyCounter a -> IncrementOnlyCounter a
increment i (IncrementOnlyCounter v) =
  IncrementOnlyCounter (Map.insertWith (\a b -> a + b + 1) i 1 v)

https://github.com/aviaviavi/legion/blob/190f6675b2d3384099a054a7a9a97784fdbbc25e/src/Lib.hs#L65

• $ a function

-- returns a copy of the block with the hash set
setBlockHash :: Block -> Block
setBlockHash block = block {blockHash = calculateBlockHash block}

-- returns a copy of the block with a valid nonce and hash set
setNonceAndHash :: Block -> Block
setNonceAndHash block = setBlockHash $ block {nonce = findNonce block}

Basic Category Theory book:

https://arxiv.org/pdf/1612.09375.pdf