Fix toArray and toList causing compilation errors

[jwosty]

Not sure if I'm doing something wrong, but toArray and toList in select expressions cause type mismatch errors for me whenever I try to use them.

I've tried this tiny little fix in my own codebase and it typechecks. It looks like more functions need fixing though. And I am also not sure how but mapSeq works in my code even though it appears to have the same issue...?

[jwosty]

Hmm. Seems it breaks some usages. For the record, I'm doing using mapSeq before the toList, maybe that has something to do with it? Roughly:

selectAsync {
    for x in table do
        select x
        mapSeq (
            // ...
        )
        toList
}

[JordanMarr]

Hi John!

I was able to recreate your issue. This also fails to build for me:

  let! results = 
      selectAsync openContext {
          for p in Person.Person do
          mapSeq $"{p.LastName}, {p.FirstName}"
          toList
      }
}

But the intended approach is to replace mapSeq into toList with mapList (or mapArray):

  let! results = 
      selectAsync openContext {
          for p in Person.Person do
          mapList $"{p.LastName}, {p.FirstName}"
      }

You may also include select p before the mapList if you want to only select certain columns:

  let! results = 
      selectAsync openContext {
          for p in Person.Person do
          select (p.LastName, p.FirstName) into selected
          mapList (
              let lname, fname = selected
              $"{lname}, {fname}"
          )
      }