It's tempting to want something like type clone Name = String type clone Currency = Int type alias Accounts = Dict Name Currency
These hypothetical "type clones" would act like their base type until you tried to use them in nonsensical ways. But trying to define their behavior is tricky. The Haskell community has apparently tried this under the name "subtypes" and concluded they are very difficult to implement and have other undesirable properties, but I couldn't find anything formal. More concretely, say one defines type clones for Length and Width in the hope of avoiding accidentally adding them, which would make no sense. But we'd want to allow multiplying them to obtain Area. The only language I know that handles this well is Frink <https://frinklang.org/>, which tracks physical units through all computations. All that said, it may be possible to define this well enough and simply enough to warrant further explanation. For example, in any correct program with type clones, one should be able to replace any clone with an alias and have identical code generated. If there's interest, I can start a new thread exploring these type clones further. -- You received this message because you are subscribed to the Google Groups "Elm Discuss" group. To unsubscribe from this group and stop receiving emails from it, send an email to elm-discuss+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
