Modified make_cons and make_frame to illustrate the pattern I

want to apply generally. This does not compile!

docs/State-of-play.md

@@ -21,6 +21,47 @@ I'm not ignoring the fact that a lot of stuff in `0.1.0` is still fundamentally
 
 I think this week is going to be mostly a thinking week — partly because the weather forecast is unusually benign, and it would be sensible get some outdoor work done.
 
+### 21:30
+
+Right, I have spent a lot of time hauling timber out of the wood today, but I've also done a substantial amount of coding, doing a sort of hybrid not-quite-standard-lisp calling convention; and I'm now convinced all this work is wrong and needs to be backed out, and I need to go for full on Lisp calling convention.
+
+So where I'm now calling `make_cons` as in this sample:
+
+```c
+struct pso_pointer c_reverse( struct pso4* frame, struct pso_pointer sequence ) {
+    struct pso_pointer result = nil;
+
+    for ( struct pso_pointer cursor = sequence; !nilp( sequence );
+          cursor = c_cdr( cursor ) ) {
+        result = make_cons( frame, c_car( cursor ), result );
+    }
+    
+    return result;
+}
+```
+
+we would instead be doing this:
+
+```c
+struct pso_pointer reverse( struct pso_pointer frame) {
+    struct pso_pointer sequence = fetch_arg( frame, 0);
+    struct pso_pointer result = nil;
+    
+    for ( struct pso_pointer cursor = sequence; !nilp( sequence );
+          cursor = cdr( make_frame( 1, frame, cursor ) ) {
+        result = cons( make_frame( 2, frame, 
+                                  car( make_frame( 1, frame, cursor )),
+                                  result);
+    }
+
+    return result;
+}
+```
+
+Note that instead of `c_reverse`, `c_cdr`, `c_car` this is using `reverse`, `cdr`, `car`. That's because these are actual Lisp functions, callable from Lisp, which don't have to be duplicated or wrapped in Lisp-compatible wrappers.
+
+This *has* to be the right way to go.
+
 ## 20260415
 
 OK, I have been diverted down a side-project on a side-project. I decided