[MLton] Type error: variable applied to wrong number of type args

[Matthew Fluet]

It seems to be related to flex-type resolution; if you add a type 
ascription to the bindtype function, the error goes away.

     and bindtype v (i, { name, reader=_, writer=_, tyvars, typ }, l) =
       case typ of
           (BIND typ) => l &&
             (if i = 0 then "    type " else
              case Vector.sub (v, i-1) of ({typ = BIND _, ... } : bind_typ) => "    and "
                                                                ^^^^^^^^^^
                                        | _ => "    withtype ")
             ++ tyvart tyvars && name && " = " ++ inline typ && "\n"
         | (DATATYPE v) => l &&
             (if i = 0 then "    datatype " else "    and ")
             ++ tyvart tyvars && name &&  " = " ++ foldli const v