🚀 go-pugleaf

hallam@zeus02.desy.de (Phillip M. Hallam-Baker) writes: 

|> I have a problem in which I want to build up a master schema from a lot
|> of little ones. The problem is tat a lot of my little schemas are going
|> to be the same. the problem comes when trying to define operations on
|> the composite system which consist of operations on two sub schemas
|> which are essentialy the same.
|>
|> For example say I have a file server system, I have a schema which
|> defines the state of the file serving robot "ROBOT" and operations
|> "MOVE_ARM_LEFT" "MOVE_ARM_RIGHT" etc. Now the complete system has two
|> robots called Fred and Harry, I want to specify the operation
|> "ALL_WAVE_ARMS" in which Fred does a MOVE_ARM_LEFT and Harry a
|> MOVE_ARM_RIGHT.
|>
|> (What about generic schemas? renaming? ... )

This king of problem comes up often, and the usual solution does not use
renaming or generic schemas.  Instead, it goes like this.  First, your
robot state schema:

	+-Robot-----
	|
	| ...
	|
	+-----------

Then, for your bunch of robots you define a state with a function from
identifiers to robots:

	[ID]

	fred, harry: ID

	+-Factory------
	|
	| assembly_line: ID -+> Robot
	|
	+--------------
	|
	| { fred, harry } \subseteq assembly_line
	|
	+---------------

Then you define operations for robots:

	+-Wave---------
	|
	| \Delta Robot
	| ...
	+--------------

Then you define something called a "framing schema" that is used to express
robot-level operations in the larger factory world.  Note that the identifier
of the robot is an input to this schema:

	+-Factory\PhiRobot---
	|
	| \Delta Factory
	| \Delta Robot
	| id?: ID
	+------------------
	| \theta Robot = assembly_line id?
	| \theta Robot' = assembly_line' id?
	+------------------

Then you can "promote" any robot-level operation to the factory level so:

	FactoryWave =^= Wave /\ Factory\PhiRobot

For example,

	FredWave =^= [ FactoryWave | id? = Fred ]

Whoops! My system's about to go down - have to close now... I was going to 
explain how to do AllWaveArms - write me if it isn't obvious.

- Jon Jacky, jon@radonc.washington.edu, Univ of Washington, Seattle, USA