Recursive function returns: Evaluation resulted in a stack overflow and cannot continue

[Anonymous]

Hi there,  

I am trying to build a function that goes through a column/list and checks whether the data stored is of type record or list. The function is below: 
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fx ColumnChecker =

let
  Source = (ListToRead as list, optional iterator as number) =>
    let
      RowCount = List.Count(ListToRead),
      i = if iterator = null then 0 else iterator,
      ListTypeCheck = Type.Is(Value.Type(ListToRead{i}), type list),
      RecordTypeCheck = Type.Is(Value.Type(ListToRead{i}), type record),
      Looper = try

          if ListTypeCheck then
            1
          else if RecordTypeCheck then
            2
          else if i >= RowCount then
            0
          else
            ColumnChecker(ListToRead, i + 1)
      otherwise
        error i
    in
      Looper
in
  Source

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The function works fine on columns that actually contain lists or records but gives me the following error on columns that contain just text/number values: 

Here is the column in question that is throwing the error: 

The result I'm expecting to get is that since the column has no record/list entries, variable i will iterate until it surpasses the RowCount ("else if i >= RowCount") at which point it will exit the loop and return 0. This process works when I put in a static number ("else if i >= 50") but I need it to be dynamic and adjust to the size of the list being passed to the function. When debugging, the error was thrown whenever i reached the RowCount (try...otherwise error i returned 348, which is the # of rows in the test data I was using)

Thanks for the help. 

@ImkeF, @Greg_Deckler @edhans @mahoneypat 

[mahoneypat · Accepted solution]

If I understand your use case, here is one way to do it.  I made this this list and called it ListToCheck

= {1,"text", {1..3}, [A="text"]}

Then used this expression that returned a value of 2 (1 list and 1 record).

= List.Count(List.Select(List.Transform(ListToCheck, each Value.Is(_, List.Type) or Value.Is(_, Record.Type)), each _ = true))

If that works, you can convert it to a function with (didn't check this one but I think it will work)

(listname as list) =>

let

x = List.Count(List.Select(List.Transform(listname, each Value.Is(_, List.Type) or Value.Is(_, Record.Type)), each _ = true))

in

x

Pat