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Thanks for the insight on this, I've edited my response. Are there any extra features in Haskell with product types? I've always understood that there was bette

• bjz_ 9y ago
  Not really. Haskell has support for higher kinded types that allow it to support lenses, which are a powerful way of declaratively traversing through data structures, so perhaps that's what you mean. On the other hand Haskell's record support is pretty woeful in comparison to languages like Ocaml, Elm, and Purescript that have support for row polymorphism. Depending on the sophistication of their implementation, row polymorphism will allow you to add and remove fields from records in a statically type checked way, and some may even allow you to pass labels around at the type level. They can even be used to model extensible variants and extensible effect types. There are creative ways to encode this in Haskell, but they all have their drawbacks, can be painful to work with, and really don't feel like a natural part of the language.
• kazagistar 9y ago
  Well, there is per-field lazyness (with the ability to opt out). So product types can let each consumer choose which parts of the result to actually evaluate and discard the rest.