Complier fails to recognize imported module.

[z5h]

X.elm

module X exposing (X)

type X
    = X Int

Y.elm

module Y exposing (..)

import X


type Thing
    = A X.X


thingToString : Thing -> String
thingToString thing =
    case thing of
        A (X.X int) ->
            "A X int"

Error is on 2nd use of X.X in Y.elm:

Cannot find pattern X.X.
No module called X has been imported.

[process-bot]

Thanks for the issue! Make sure it satisfies this checklist. My human colleagues will appreciate it!

Here is what to expect next, and if anyone wants to comment, keep these things in mind.

[process-bot]

Thanks for the issue! Make sure it satisfies this checklist. My human colleagues will appreciate it!

Here is what to expect next, and if anyone wants to comment, keep these things in mind.

[evancz]

When you say exposing (X) you are only exposing the type, not the constructors. You must say exposing (X(..)) to reveal the constructors as well. This allows you to hide details if you want, and it is very important to creating strong abstractions. I recommend asking around on Slack for further details.

So there is no bug here, but that is certainly a weird error message. This is a good candidate for https://github.com/elm-lang/error-message-catalog/issues Can you put it there?

[evancz]

When you say exposing (X) you are only exposing the type, not the constructors. You must say exposing (X(..)) to reveal the constructors as well. This allows you to hide details if you want, and it is very important to creating strong abstractions. I recommend asking around on Slack for further details.

So there is no bug here, but that is certainly a weird error message. This is a good candidate for https://github.com/elm-lang/error-message-catalog/issues Can you put it there?

[martian57]

I am new to elm. Exposing the constructors work, but a slight modification to the code cause the compiler to fail:

X.elm:

module X exposing (XType(..))

type XType
    = X1 Int

Y.elm:

module Y exposing (..)

import X


type Thing
    = A X.XType


thingToString : Thing -> String
thingToString thing =
    case thing of
        A (X.XType int) ->
            "A X int"

results in

Cannot find pattern `X.XType`.

13|         A (X.XType int) ->
               ^^^^^^^^^^^
`X` does not expose `XType`. 

[martian57]

I am new to elm. Exposing the constructors work, but a slight modification to the code cause the compiler to fail:

X.elm:

module X exposing (XType(..))

type XType
    = X1 Int

Y.elm:

module Y exposing (..)

import X


type Thing
    = A X.XType


thingToString : Thing -> String
thingToString thing =
    case thing of
        A (X.XType int) ->
            "A X int"

results in

Cannot find pattern `X.XType`.

13|         A (X.XType int) ->
               ^^^^^^^^^^^
`X` does not expose `XType`. 

[jvoigtlaender]

Try replacing A (X.XType int) by A (X.X1 int).

[jvoigtlaender]

Try replacing A (X.XType int) by A (X.X1 int).