src/Main.hs:34:12: error:
    • Couldn't match expected type ‘Turtle.Shell.FoldShell
                                      (Either Turtle.Line.Line Turtle.Line.Line) r0
                                    -> IO r0’
                  with actual type ‘Either (Shell Turtle.Line.Line) b0’
    • In the pattern: Left line
      In the pattern: Shell (Left line)
      In a case alternative: Shell (Left line) -> line
   |
34 |     Shell (Left line)  -> line
   |            ^^^^^^^^^

src/Main.hs:35:12: error:
    • Couldn't match expected type ‘Turtle.Shell.FoldShell
                                      (Either Turtle.Line.Line Turtle.Line.Line) r1
                                    -> IO r1’
                  with actual type ‘Either a0 (Shell Turtle.Line.Line)’
    • In the pattern: Right line
      In the pattern: Shell (Right line)
      In a case alternative: Shell (Right line) -> line
   |
35 |     Shell (Right line) -> line
   |            ^^^^^^^^^^