A new type 'Future' now statically rules out any misuses of 'changes'. It is no longer necessary to tie a knot.
Latches are now recalculated using a cache with timestamps.

The new module 'Reactive.Banana.Prim.Dated' implements this cache. Unfortunately, the current code reintroduced the foldl-like space leak.
Latch accumulation does not display the foldl-like space leak anymore. #52

The 'Box' type still allows lazy evaluation when using 'fmap' or the Control.Applicative combinators.