Make `Set a` and `Dict a ()` be different types?

[jvoigtlaender]

Currently they are not. Which means that expressions like Dict.get 5 (Set.singleton 7) etc. are type-correct, even though:

• they make no sense (the particular given one makes specifically little sense, since Set does not itself have a get function)
• the documented APIs suggest that these expressions should not be valid (types of Dict.get and Set.singleton are completely incompatible, as far as a reader of http://package.elm-lang.org/packages/elm-lang/core/latest/Dict and http://package.elm-lang.org/packages/elm-lang/core/latest/Set is concerned).

[jvoigtlaender]

BTW, I conjecture Set a and Dict a () are currently only accidentally not distinguished, similarly as in #234, where Evan indicated that at same point in the past it wasn't clear whether type aliases (which are at play here) would behave like Haskell's type or like Haskell's newtype.

[jvoigtlaender]

BTW, I conjecture Set a and Dict a () are currently only accidentally not distinguished, similarly as in #234, where Evan indicated that at same point in the past it wasn't clear whether type aliases (which are at play here) would behave like Haskell's type or like Haskell's newtype.

[jvoigtlaender]

Closed via https://github.com/elm-lang/core/pull/263.

[jvoigtlaender]

Closed via https://github.com/elm-lang/core/pull/263.

[evancz]

Oh, also, this means that the toString function is messed up for now. We may want to give the internal constructor a weirder name when we fix that!

[evancz]

Oh, also, this means that the toString function is messed up for now. We may want to give the internal constructor a weirder name when we fix that!

[jvoigtlaender]

So currently it will say something like Set (Dict.fromList [(0,())]) instead of Set.fromList [0]? Well, probably better to fix that, yes. Though I must say looking at the implementation of toString in the native JS code right now, I'm a bit scared overall. I mean, it seems that if somebody decided to have a constructor named RBNode in their own union type, results could be quite catastrophic?

[jvoigtlaender]

So currently it will say something like Set (Dict.fromList [(0,())]) instead of Set.fromList [0]? Well, probably better to fix that, yes. Though I must say looking at the implementation of toString in the native JS code right now, I'm a bit scared overall. I mean, it seems that if somebody decided to have a constructor named RBNode in their own union type, results could be quite catastrophic?

[jvoigtlaender]

Indeed, this leads to a runtime error:

import Graphics.Element

type V = RBNode

v = RBNode

main = Graphics.Element.show v

[jvoigtlaender]

Indeed, this leads to a runtime error:

import Graphics.Element

type V = RBNode

v = RBNode

main = Graphics.Element.show v