Yes!  I think perhaps that f needs only to be a homomorphism instead of an isomorphism, but I don&#x27;t trust myself enough to make such a claim definitively :)<p>Always curious to follow people doing compiler work; loop me in, yeah?<p>And, just watched that Wadler talk; it&#x27;s good stuff.  Of course, it sounds like his scenario is like: &quot;there is a way to do the transformation, you just have to find it,&quot; and in my case, it&#x27;s more like: &quot;there might or might not be an algebra in which f acts as a homomorphism, and, even if there is, you may not have the transformations you need to determine it!&quot;