typechecker

ES imports and exports can only be used at the top level of a module. This is illegal:

function container() {
  import 'fs'
  export { container }
  namespace N { }
}

The current errors for these three statements are vague and, for JS, contain irrelevant terms:

Actual:

(1) "An import declaration can only be used in a namespace or module."
(2) "An export declaration can

Elm has the option to output errors as JSON (via a flag), and something like that is handy for writing tooling around it. I'm trying to integrate pytype into ALE and this would make it a lot easier.

Handle types with free variables, for example:

-type foo :: {_Foo, _Bar}.

Free variables should be replaced with any()