
  Syntax error!
  syntax_tests/data/parsing/errors/structure/external.res:2:51

  1 │ // missing JS value name
  2 │ external setTimeout: (unit => unit, int) => float =
  3 │ 

  An external requires the name of the JS value you're referring to, like "setTimeout".

external setTimeout : (unit -> unit (a:1)) -> int -> float (a:2)