Jvacux.hs now defines two monadic types made with mtl's ReaderT, one containing an Error monad and the other not.  This should hopefully allow the rest of the code to be rewritten in a way better suited to returning error messages while selectively retaining non-strict evaluation.
Jvacux.hs now defines two monadic types made with mtl's ReaderT, one containing
an Error monad and the other not.  This should hopefully allow the rest of the
code to be rewritten in a way better suited to returning error messages while
selectively retaining non-strict evaluation.

jwodder/jbobaf,jwodder/jbobaf,jwodder/jbobaf