- Datatype package now also supports arbitrarily branching datatypes
(using function types).
- Added new simplification procedure for proving distinctness of
constructors.
- dtK is now a reference.
consts fib :: nat => nat
recdef fib "measure(%n. n)"
"fib 0 = 0"
"fib 1 = 1"
"fib (Suc(Suc x)) = fib x + fib (Suc x)"