Cannot have two messages with the same parameter name of different types

[NorfairKing]

Test1 a@Text: #{a}
Test2 a@Int: #{show a}

Results in:

    • Constructors MsgTest1 and MsgTest2
      give different types for field
      ‘appMessageA’
    • In the data type declaration for ‘AppMessage’

[parsonsmatt]

That's a GHC restriction, actually - it's trying to generate a record like:

data AppMessage 
    = MsgTest1 { appMessageA :: Text }
    | MsgTest2 { appMessageA :: Int }

which GHC rejects, since the term appMessageA now has two conflicting types (as a field accessor).

shakespeare could probably throw a more informative error if it detects this case, or provide a "field name customization option" that would make these distinct, or simply not generate field labels like this, or expect DuplicateRecordFields + NoFieldSelectors and nested datatypes instead of a single sum.

[NorfairKing]

@parsonsmatt
Thanks for the explanation.
What is the appMessageA field used for?
Perhaps it could just be an unnamed field?
This would be safer as well.

[parsonsmatt]

I'm not familiar with the codebase really, but I'd guess that the templating uses a record field name to access the value, since that tends to be easier to generate code for than pattern matching with fresh names