Reasonml type with multiple arguments, Error exception Failure("nth")

Question

I have got Error while compiling the following code

type shape =
  | Circle int
  | Square int
  | Rectangle int int;

let myShape = Circle 10;

let area =
  switch myShape {
  | Circle r => float_of_int (r * r) *. 3.14
  | Square w => float_of_int (w * w)
  | Rectangle w h => float_of_int (w * h)
  };

Js.log area;

Fatal error: exception Failure("nth")
ninja: build stopped: subcommand failed.

When I change the Rectangle to tuple (int, int), it works

type shape =
  | Circle int
  | Square int
  | Rectangle (int, int);

let myShape = Circle 10;

let area =
  switch myShape {
  | Circle r => float_of_int (r * r) *. 3.14
  | Square w => float_of_int (w * w)
  | Rectangle (w, h) => float_of_int (w * h)
  };

Js.log area;

Is it not possible to have multiple arguments on a data constructor?

thanks

Issue has been submitted to buckelscript https://github.com/BuckleScript/bucklescript/issues/1822

Answer 1

Both variants are perfectly valid Reason code. You can have constructors with multiple arguments, and you're doing it right. Apparently, the problem is in the Js.log function, that is sort of a magic function and with the n-ary constructors,the magic fails.

So, my suggestion is (i) to submit an issue in the bucklescript bug tracker and (ii) do not use the magic Js.log function, but rather derive or write your own printer function and use it.