Excel

Excel support has two interfaces:

• ExcelReader opens an .xlsx file.
• Workbook is the open, sheet-wise handle it returns.

FileSystem.openWorkbook is a shortcut through the ambient excelReader capability. Generated code can inspect a large workbook without putting every cell into model context.

def runTask(): Unit receives stdout, fs, excelReader =
  match fs.openWorkbook("orders.xlsx")
  case Err(error) => println: error
  case Ok(book) =>
    for sheet in book.sheets do println: sheet

    match book.rows("Orders", 1, 20)
    case None       => println: "No Orders sheet"
    case Some(rows) =>
      for row in rows do println: row.join(" | ")

    book.close()

Rows are 1-based. Close the workbook when finished.

Inspect a sheet’s dimensions before choosing a row window. An unknown sheet returns None; a window beyond the end reads short. Cells are rendered as strings, with empty cells returned as "".

The shipped OpenpyxlExcel backend opens workbooks in read-only streaming mode and returns cached formula values rather than formulas. It is backed by openpyxl:

excelReader = new OpenpyxlExcel(root)

Replace the ExcelReader binding in SandboxRuntime.jo to use another implementation. Generated code continues to use fs.openWorkbook and the Workbook interface.

Interface reference

interface ExcelReader
  def open(src: String): Result[Workbook, String]
end

interface Workbook
  def sheets: List[String]
  def dimensions(sheet: String): Option[Workbook.SheetSize]
  def rows(sheet: String, start: Int, count: Int): Option[List[List[String]]]
  def close(): Unit
end

param excelReader: ExcelReader

section Workbook
  class SheetSize(rows: Int, columns: Int)
end