Modules are permitted to re-export a type class and a type of the same name #3502
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Presumably then the plan is to fix this by disallowing it? That will be a breaking change, so shall we label it |
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Sure thing |
joneshf
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Within a module, we cannot define a class and a data type with the same name. The issue here is that we can define a class and a data type with the same name in different modules, then re-export them both from one module. We don't want to allow this behavior. We add a failing test to codify that this should not work.
joneshf
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As mentioned in the previous commit (09bfea484ff6e0d77c028f11314763c794df8c47), we don't want to allow re-exporting a class and a type that have the same name. The changes here make that a reality. The majority of the tests are breaking because we're dependent on `purescript-typelevel-prelude` and it violates the changes here. See: purescript/purescript-typelevel-prelude#43 for more information.
joneshf
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Before, we only had conflicting exports for the same types of things. Now that we disallow exports of different types, we'll want to be a bit more explict in what the problem is. Errors we'd get before looked like: ``` Export for type B.X conflicts with A.X ``` While that does convey what the problem is, we can do a bit better. Errors now look like: ``` Export for type B.X conflicts with type class A.X ```
joneshf
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The changes to `purescript-typelevel-prelude` allow us to pass tests. The transitive dependency on `purescript-prelude` required an update.
hdgarrood
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Refs #43, fixes #46. RowList-related types and classes have been removed from Type.Row and moved into Type.RowList, in order to prepare for an upcoming compiler change whereby a module will no longer be allowed to re-export both a type and a class of the same name; see purescript/purescript#3502
hdgarrood
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* Add failing test for conflicting re-exports (#3502) Within a module, we cannot define a class and a data type with the same name. The issue here is that we can define a class and a data type with the same name in different modules, then re-export them both from one module. We don't want to allow this behavior. We add a failing test to codify that this should not work. * Disallow re-exporting same class/type name (#3502) As mentioned in the previous commit (09bfea484ff6e0d77c028f11314763c794df8c47), we don't want to allow re-exporting a class and a type that have the same name. The changes here make that a reality. The majority of the tests are breaking because we're dependent on `purescript-typelevel-prelude` and it violates the changes here. See: purescript/purescript-typelevel-prelude#43 for more information. * Print the type of the conflicting name (#3502) Before, we only had conflicting exports for the same types of things. Now that we disallow exports of different types, we'll want to be a bit more explict in what the problem is. Errors we'd get before looked like: ``` Export for type B.X conflicts with A.X ``` While that does convey what the problem is, we can do a bit better. Errors now look like: ``` Export for type B.X conflicts with type class A.X ``` * Update dependencies (#3502) The changes to `purescript-typelevel-prelude` allow us to pass tests. The transitive dependency on `purescript-prelude` required an update.
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This was fixed by #3648. |
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Currently, it's possible to re-export a type and a type class of the same name from a module, even though it's not possible to define a type and a type class of the same name together in one module. For example,
There is an example of this in
purescript-typelevel-preludeat version 3.0.0, where the moduleType.Rowre-exports the classConsfromPrim.Rowas well as the typeConsfromPrim.RowList. At the moment, this is only a minor issue; as far as I'm aware, the only problem this can cause is that it can break anchor links in docs. However, if we ever want to do #1888 (which do still I think we should), I think we will need to make this an error.The text was updated successfully, but these errors were encountered: