remove accidentally added file
add runRegister method; simplification in TestEnv
simplification
simplification
tweak global state
refactoring
refactoring
simplification: remove Register type class
add ReaderT instances
generalize onChangeEq
eliminate postponeModification
move instance definitions
eliminate askPostpone
cleanup
refactoring: don't depend on outer postpone
cleanup
refactoring
fix two bugs
fix a bug
add Demo app