Re: [Haskell-beginners] How do I do inheritance in haskell?

I think that's a bit over the top, because why shouldn't prices and volumes be interchangeable between Asks and Bids?

It's a good question. I guess as long as a price / volume is always wrapped in a type that's tagged bid / ask then everything is great. You just want to avoid being the next knight capital and ending up trading the wrong side of the spread.