Glossary

Word	Meaning	Page
kind	a type of thing, with fields, spawns and sinks	Kinds and fields
instance	yen.<kind>.<name>: one thing of a kind	Kinds and fields
field	a typed datum of each instance	Types and defaults
type	any value with check = value: bool	Types and defaults
ref	a field value that is another instance	Instances and refs
data kind	a kind that no kind spawns: instances with no scope	Instances and refs
root kind	the kind that nothing spawns, and that spawns others	Scopes and spawns
scope	one instance at one place in the tree; its id is its path	Scopes and spawns
spawns	a function from a parent scope to the instances under it	Scopes and spawns
aspect	behavior: active where at holds, gives elements by key	Aspects
predicate	a function of a scope, or a kind, instance, aspect or list	Predicates
element	one value an aspect gives to a sink	Aspects
sink	collects elements at a receiver and reduces them	Sinks and reduce
receiver	the nearest ancestor-or-self scope with the sink, where its at holds	Routing and walls
wall	a sink with no keys: elements stop there	Routing and walls
forward	a sink key that names another sink and feeds it	Forwards
arg	a named arg of an element: a kind, a sink, scope, or open	Args
component	an aspect’s cycle: sources in, sinks out, 0 to n elements	The cycle form
error record	an error as data, with code, fix and class	Errors as data
query	an answer of eval: errors, graph, active, reduced, …	Queries
invariant	Datalog rules over the facts; a true bad: atom is a violation	Invariants
stored query	a named question, asked with r.ask	Stored queries
stage	the fleet without and with a change, compared	Stage a change
grant	where a change may give elements; grants only narrow	Stage a change
change program	a change as data ops: set, ref, place, new	Change programs
knowledge pack	the fleet as sorted N-Triples with a sha256	Knowledge packs