Annotated execution

.gitignore

@@ -7,3 +7,4 @@ dist-newstyle/
 .stack-work
 .cabal.sandbox.config
 .envrc
+foo.js

examples/circular_hos.hs

@@ -17,6 +17,24 @@
 -- >   --hide-selector-thunk-opt \
 -- >   --javascript foo.js \
 -- >   -i examples/circular_hos.hs
+--
+-- Annotated execution (as of a59bccb):
+--
+--  2. As soon as we demand the value of @maxBV body_0@ to determine the
+--     variable to be used for the outer-most lambda, this will force the
+--     construction of the next term down. This happens recursively, so the
+--     entire term is build in memory.
+-- 14. This is an instructive subsequence: we will see the evaluation of
+--     the simple term @lam (\y -> y)@.
+-- 20. At this point this term is fully known: @Lam 1 (Var 1)@.
+-- 21. The computation is driven by the computation of the variable to be used
+--     for the outermost lambda; we can now continue this computation a little
+--     bit, because we now know the @maxBV@ of the subterm @Lam 1 (Var 1)@.
+-- 22. We repeat for the second simple term @lam (\z -> z)@.
+-- 32. At this point we're almost done: we need to know the @max@BV@ of the
+--     subterm @Var n_1@, but there aren't any, so that is just @0@.
+-- 34. At this point all bound variables are known, and the new term has been
+--     constructed.
 maxBV = (\exp ->
     case exp of {
         Var x   -> 0

examples/repmin.hs

@@ -14,6 +14,22 @@
 -- >   --hide-selector-thunk-opt \
 -- >   --javascript foo.js \
 -- >   -i examples/repmin.hs
+--
+-- Annotated execution (as of a59bccb):
+--
+--  1. One way to think about this circular program is to consider that it
+--     first creates a pointer to an int (the new value in the leaves), and
+--     then starts building up a tree with all leaves pointing to this int;
+--     as it builds the tree, it is also computing the value of this int.
+--  6. We're starting to see the tree take shape here; the top-level structure
+--     of the tree is now known.
+-- 10. Similarly, we now see the shape of the left subtree.
+-- 13. Here we see the first @Leaf@, ponting to @m_1@; part of the computation
+--     of @m_1@ is now also known (@mb_7@).
+-- 16. The second @Leaf@ is known.
+-- 18. The minimum value of the left subtree is known (@mb_4@).
+-- 28. At this point the structure of the tree is mostly done. We can
+--     finish the value computation.
 worker = (\m -> \t ->
       case t of {
           Leaf x -> Pair x (Leaf m)