# out is not allocated
fn read-cell in: (addr gap-buffer), _out: (addr handle cell) {
  # TODO:
  #   tokenize
  #   insert parens
  #   transform infix
  #   token tree
  #   syntax tree
  rewind-gap-buffer in
  # read symbol
  var out/eax: (addr handle cell) <- copy _out
  new-symbol out
  var out-a/eax: (addr cell) <- lookup *out
  var out-data-ah/eax: (addr handle stream byte) <- get out-a, text-data
  var _out-data/eax: (addr stream byte) <- lookup *out-data-ah
  var out-data/edi: (addr stream byte) <- copy _out-data
  {
    var done?/eax: boolean <- gap-buffer-scan-done? in
    compare done?, 0/false
    break-if-!=
    var g/eax: grapheme <- read-from-gap-buffer in
    write-grapheme out-data, g
    loop
  }
}