Conflict between nested modules/types?

[cmeeren]

(cc @Zaid-Ajaj)

In the new theme DSL, I have this:

module theme =

  type palette =
    static member inline primary (color: Color) : IThemeProp = unbox ("palette.primary", color)

  module palette =

    [<Erase>]
    type primary =
      static member inline main (color: string) : IThemeProp = unbox ("palette.primary.main", color)

Unfortunately, it seems that for some reason, this does not allow using theme.palette.primary.main:

Here's a minimal repro:

module test=

  type a =
    static member inline b x = x

  module a =

    type b =
      static member inline c x = x

// Doesn't compile
let x = test.a.b.c
//               ^ The field, constructor or member 'c' is not defined

// Compiles
open test
let x = a.b.c

Does anyone have any idea why, and if it can be circumvented? Currently things aren't looking good for the flattened theme DSL...

[Zaid-Ajaj]

Maybe try to define the module palette before the type palette?

Edit

Doesn't work, just tried it

[Zaid-Ajaj]

I can't test the following in the REPL but maybe it would help to add type palette as an extension type for module theme in a different file. i.e.

// File A
module test =
  module a =
    module b =
      let inline c x = x

// File B
module test = 
    type a = 
        static member inline b x = x

[cmeeren]

Nope, still fails. (VS gives no error, but Fable compilation fails with the same error.)

[cmeeren]

Reported as F# compiler issue here: https://github.com/dotnet/fsharp/issues/8432

[Shmew]

Yeah, this is because of the way the compiler resolves types. It picks out the first value that works, which means if you have three levels of nesting it stops working. It's why I had to change the dsl I used in Feliz.Plotly

[cmeeren]

Could you briefly describe how you solved it?

[Shmew]

I traversed the schema to find things that were unique and nested them inside the different properties, and everything else was top level. So before it would have been something like:

scatter.font [ 
    scatter.font.size 10 
]

where every level of nesting was getting longer, but now it is like this:

scatter.font [
    font.size 10
]

Once I had something that was deeper than three levels (so any more nesting than above) it would stop working and I had to use module aliasing to fix it. Luckily for me almost everything the different charts used were almost the same.

[cmeeren]

The only collisions are the stuff under palette, and I seem to be able to solve it by just renaming the modules. My preferred solution right now:

theme.palette.primary Colors.indigo  // as normal
theme.palette.primary'.main "#aabbcc"  // note the extra apostrophe

This allows the DSL to otherwise stay consistent.