Haskell itself was created starting in 1990. Haskell '98 is referring to the 1998 report which was a popular standard for Haskell. It's not the first standard for Haskell nor was it the last (2010).
Okasaki and Bagwell did a lot to expand and firm up knowledge on persistent data structures, but there have been persistent search trees (usable for hash-maps) for ages. Lists too.
Okasaki and Bagwell did a lot to expand and firm up knowledge on persistent data structures, but there have been persistent search trees (usable for hash-maps) for ages. Lists too.