Cool, thanks for the explanation. I guess I'm a little confused by the desire to "derive many functions on different data-structures automatically". What's the

Cool, thanks for the explanation. I guess I'm a little confused by the desire to "derive many functions on different data-structures automatically". What's the independant variable in this meta-function? It makes little sense to "automatically" define a type when one could argue that programming is the act of defining types! I guess my claim is that I want to express type as a named list of predicates that fold into a single predicate over 'and'.