Update join syntax
Extract code to build a requires clause
Upgrade nippy
Add :type to expr$
Add fold
Add finalf to fold-fn
Change fold execution strategy & add builtin fold operators
Use consistent ids for folded fields
Initialize UDF via constructor
Simplify pigpen.code/trap - now includes requires within re-written form
Fix fold threading order and add docs
Fix nippy header suppression
Allow ambiguity in single arg min/max overload
Polish docstrings
Fix juxt
Fix java style warnings
Upgrade nippy
Add TODO
Update docstrings
Update fold tests