anchor.diff:          // OPTIMIZE : The functions below could be modified to include an optimized case
           // for when the separator array contains just a single character.
   
  -        (*
  -        - String.Split.filter
  -        - String.Split.choose
  -          - These functions should work like .Split(...) |> Array.iter (or Array.fold, etc.),
  -            except that they won't actually need to traverse the entire string first and split
  -            it into an array of substrings. Instead, they'll improve performance by allowing us
  -            to execute a function on each of the substrings in a single forward pass.
  -          - Performance is improved with these functions because they'll be applied to Substring
  -            values instead of creating the substrings as separate objects.
  -        *)
  -
           /// Determines if the StringSplitOptions.RemoveEmptyEntries flag is set in the given value.
           let inline private skipEmptyStrings (options : System.StringSplitOptions) =
               Enum.hasFlag StringSplitOptions.RemoveEmptyEntries options
  
positive.code:         /// substrings in the input string. For example, if the newline character (\n) is used
          /// as the separator, the index of each substring would be the line number.
          [<CompiledName("IterIndexed")>]
          let iteri (separator : char[], options : System.StringSplitOptions) (action : int -> substring -> unit) (str : string) : unit =
              // Preconditions
              checkNonNull "str" str
  
              // TODO
              notImpl "String.Split.iteri"
  
          //
          [<CompiledName("Fold")>]
          let fold (separator : char[], options : System.StringSplitOptions) (folder : 'State -> substring -> 'State) (state : 'State) (str : string) : 'State =
              // Preconditions
              checkNonNull "str" str
  
              // TODO
              notImpl "String.Split.fold"
  
          //
          [<CompiledName("FoldIndexed")>]
          let foldi (separator : char[], options : System.StringSplitOptions) (folder : 'State -> int -> substring -> 'State) (state : 'State) (str : string) : 'State =
              // Preconditions
              checkNonNull "str" str
  
              // TODO
              notImpl "String.Split.foldi"
  
  
  //
  
negative.code:         /// Applies the given function to each of the substrings in the input string that are
          /// delimited by elements of a specified Unicode character array.
          [<CompiledName("Iter")>]
          let iter (separator : char[], options : StringSplitOptions)
                  (action : substring -> unit) (str : string) : unit =
              // Preconditions
              checkNonNull "str" str
  
  