iter-yield from lambda currently broken

[okamsn]

As of the time of writing, iter-yield doesn't work in lambdas or when sharp quoted inside of iter-defun or iter-lambda. As a consequence, iter-yield doesn't work with seq-do, seq-doseq, and other mapping functions and macros which expand to such.

As a consequence of that, iterators cannot currently be used to work around the limitations of seq-do, mapatoms, and other methods that we might wish to use to produce sequence elements without producing an intermediate list, as desired in #134 and #135.

This has been reported upstream by another Emacs user (https://debbugs.gnu.org/cgi/bugreport.cgi?bug=59140).