Warning found:
in module Main
at tests/purs/warning/4183.purs:4:1 - 4:21 (line 4, column 1 - line 4, column 21)

  The inferred kind for the type declaration T contains polymorphic kinds.
  Consider adding a top-level kind signature as a form of documentation.
                                          
    type T :: forall k. (k -> k) -> k -> k
                                          

in type synonym T

See https://github.com/purescript/documentation/blob/master/errors/MissingKindDeclaration.md for more information,
or to contribute content related to this warning.