+- attributes for fields and local variables
+ transparent - names inside can be accessed directly
+
+ handled - accesses convert to function calls??
+ constant - compile time constant - not stored
+ stable - ??
+ add-only - ?? like append-only.
+ read-only - set early never changed?
+ mutable
+ owned - Can be borrowed and freed
+ borrowed - There is somewhere this is borrowed from
+ dependant - ???
+ pure - definitely not an error
+ endian(big,small,pdp)
+ attributes for whole struct
+ unsorted - fields appear as written
+ packed - like unsorted, but no gaps permitted.
+
+- lambda functions for passing as arg to function.
+ Are these always there to provide an interface for a value?
+ Do I want a syntax for functions that just provides a value
+ func (a:number; b:string):number = a+b[]
+
+- units for numbers
+- iso suffixes for number?
+- static variables. Easy to implement, but need a syntax. Something
+ really loud.
+- concurrency
+ implicit and explict
+ reference attributes for locks and refcounts etc
+ RCU
+ - do/go/run/fork/async complex statement
+ All local variables accessed in the body are read-only
+ and copied to a new frame, and code is run in a new thread.
+ Thread is mostly invisible. It interacts through shared objects,
+ particularly the caller might create a channel and the thread
+ might send messages on it. Any interesting handshakes
+ are mediated by appropriate data structures.
+
+- arbitrary value asserts tied to variable attributes.
+ e.g. ranges for value and relationships between fields
+ These are tested by compiler at any changed. Somehow.
+
+- expose parse info for editing by code run at compile time.
+ This allows new attributes to be implemented in app code.
+ E.g. handling bigendian fields by adding conversion functions.