My languages of choice do make creating custom data structures at least as easy as Haskell, and I still rarely do it. In most cases I've found it's faster in i

My languages of choice do make creating custom data structures at least as easy as Haskell, and I still rarely do it. In most cases I've found it's faster in implementation time, testing time, and running time to just use built in data structures when possible. Even in Haskell.