Laziness.
Memoization in ObjC
Usage of delaying.
1-line memoize.
Nullability in ObjC.
Don’t need to explain why laziness/memoization break down in such detail.
That should’ve been bold all along.
Only discuss nullability in the nullability §.
Revisit nullability with fixpoints.
Parse forest in ObjC.

Reformat later.
Compaction in ObjC.
Reformat parseForest.