[cells-gtk-devel] New Cells Use Case, comments welcome
Kenny Tilton
ktilton at nyc.rr.com
Wed May 18 18:35:17 UTC 2005
Sorry for spaming all the groups, but the occasion (Cells doc) is rare
enough I thought everyone should be included. From here on is a
standalone example (with Cells loaded) that reads data from itself.
It models tracking of an index of stocks. I plan a few more notes, but
thought I would invite comments/requests for clarification now. Here goes:
(in-package :cells)
#|
The deal is this: explanations of chunks of code appear /below/ them.
Now here are Ron's functional requirements: process a stream of messages
from an
imagined source of financial data. Actually, Ron has an intermediate process
reading a real source and producing a somewhat-digested stream in
Lisp-friendly
format. Sample:
(:date 5123 :weekday 3)
(:index ((AA 29.30 7.3894672) (AIG 53.30 7.3894672)(AXP 53.00 7.3894672)
(BA 59.87 7.3894672) (C 46.80 7.3894672) (CAT 87.58 7.3894672) (DD 47.74
7.3894672)
(DIS 26.25 7.3894672) (GE 36.10 7.3894672) (GM 27.77 7.3894672) (HD
36.75 7.3894672)
(HON 35.30 7.3894672) (HPQ 21.00 7.3894672) (IBM 76.47 7.3894672)
(INTC 23.75 7.3894672) (JNJ 68.73 7.3894672) (JPM 35.50 7.3894672) (KO
43.76 7.3894672)
(MCD 29.80 7.3894672) (MMM 76.76 7.3894672) (MO 65.99 7.3894672) (MRK
34.42 7.3894672)
(MSFT 25.36 7.3894672) (PFE 27.5 7.3894672) (PG 54.90 7.3894672) (SBC
23.8 7.3894672)
(UTX 100.96 7.3894672) (VZ 36.75 7.3894672) (WMT 48.40 7.3894672) (XOM
56.50 7.3894672)))
(:trade INTC 0.001932 :last 23.75)
(:trade MSFT 0.001932 :last 25.36)
(:trade INTC 0.011931 :last 23.75)
(:trade MSFT 0.011931 :last 25.36)
(:trade MSFT 0.041965 :last 25.32)
(:trade UTX 0.067027 :last 101.39)
...etc...
Date messages encode date as (+ (* (- year 2000) 1000) julian-days).
Weekday is dicey,
so the tutorial deduces the Lisp weekday and stores that.
Index messages define which tickers are in the index and their weights.
Entries are: (ticker-symbol initial-price index-weight)
Trade messages are (ticker-symbol ticker-minute :LAST price)
Ticker-minute is time since open, in minutes. Negative indicates
pre-open trading.
To get the ball rolling, we just want to print out each trade as
received, with the
addition of an indicator as to which way the price moved: -1, 0, or 1
for down, unchanged, or up.
For the index, we want to track the minute of the last trade affecting
the index, the
weighted index value, and the last move of each index entry.
|#
(defparameter *trc-trades* t)
#+test
(run-trading-day)
(defun run-trading-day ()
(cell-reset)
(let ((*trc-trades* nil)
(t-day (make-be 'trading-day)))
;; - always call CELLS-RESET when starting a test run
;; - (make-be ...) -> (to-be (make-instance ...))
;; - TO-BE jumpstarts a Cells instance into the flow. (FN to-be)
#+not (with-open-file (t-data (make-pathname
:directory '(:absolute "0dev" "cells"
"Use Cases" "dow-jones")
:name "stock-exchange" :type "lisp"))
(with-metrics (nil t "run-trading-day")
(loop for message = (read t-data nil :eof)
until (eq message :eof)
do (setf (message t-day) message)))
)
(with-open-file (t-data (make-pathname
:directory '(:absolute "0dev" "cells" "Use
Cases" "dow-jones")
:name "stock-exchange" :type "lisp"))
(with-metrics (t t "run-trading-day")
(loop with in-data = nil
do (if (not in-data)
(setf in-data (msg-start (read-line t-data nil :eof)))
(let ((message (read t-data nil :eof)))
(count-it :dow-message)
(if (eql (car message) :close)
(loop-finish)
(setf (message t-day) message)))))))
(trc "index value = " (value (car (indexes t-day))))))
;; --- trading day ---------------------------------
;;
(defmodel trading-day ()
((message :initarg :message :accessor message
:initform (c-in nil) ;; c-in -> c-input, how data enters a model
(see FN c-input)
:cell :ephemeral) ;; handling transient phenomena in a steady-state
paradigm (FN ephemeral)
(date :initarg :date :accessor date
:initform (c? (or .cache ;; advanced trick using prior value (see
FN date/.cache)
(when (eql :date (car (^message)))
(destructuring-bind (&key date weekday)
(^message)
(declare (ignore weekday)) ;; derive from date
(encode-julian-date (+ 2000 (floor date 1000))
(mod date 1000)))))))
(weekday :initarg :weekday :accessor weekday
:initform (c? (when (^date)
(multiple-value-bind (second minute hour date month
year day daylight-p zone)
(decode-universal-time (^date))
(declare (ignorable second minute hour date month
year daylight-p zone))
day))))
;; not much new here, but astute readers will wonder if this cell
gets optimized away
;; when (^date) on its second evaluation uses its .cache and gets
optimized away.
;;
;; yes. Just checked to be sure.
(trade :cell :ephemeral :initarg :trade :accessor trade
:initform (c? (when (eql :trade (car (^message)))
(message-to-trade (^message)))))
;;
;; nothing new here, but note that again we use the :ephemeral option
;;
(indexes :initarg :indexes :accessor indexes
:initform (c? (with-c-cache ('cons)
(when (eql :index (car (^message)))
(make-be 'index
:trading-day self
:index-def (second (^message)))))))
(tickers :cell nil :reader tickers :initform (make-hash-table
:rehash-size 50))
))
(def-c-output trade ((self trading-day) trade) ;; FN def-c-output
(when trade ;; FN trade setf optimization
(push trade (trades (ensure-ticker self (trade-ticker-sym trade))))))
(defun trading-day-ticker (day sym)
(gethash sym (tickers day)))
(defun (setf trading-day-ticker) (ticker day sym)
(setf (gethash sym (tickers day)) ticker))
(defun ensure-ticker (trading-day ticker-sym &optional price minute)
(or (trading-day-ticker trading-day ticker-sym)
(setf (trading-day-ticker trading-day ticker-sym)
(make-be 'ticker :ticker-sym ticker-sym
:trades (c-in (when price
(list (make-trade :ticker-sym ticker-sym
:minute minute :price price))))))))
(defmodel ticker (model)
((ticker-sym :cell nil :initarg :ticker-sym :reader ticker-sym)
(trades :initarg :trades :accessor trades :initform (c-in nil))
(last-move :reader last-move
:initform (c? (bwhen (penult-trade (second (^trades)))
(let ((last (trade-price (first (^trades))))
(penult (trade-price penult-trade)))
(cond
((< last penult) -1)
((= last penult) 0)
(t 1)))))
:documentation "Price up, down, or unchanged as 1, -1, or zero")))
;;
;; Small point: there is no problem with accessing a dependency twice,
as above.
;;
(defun ticker-price (ticker)
(bwhen (trade (car (trades ticker)))
(trade-price trade)))
(defun ticker-trade-minute (ticker)
(bwhen (trade (car (trades ticker)))
(trade-minute trade)))
(def-c-output trades ((self ticker)) ;; FN trades def-c-output
(when *trc-trades*
(loop for trade in (set-difference new-value old-value)
do (format t "~&at ~a min, ~a at ~a, change ~a"
(trade-minute trade) (ticker-sym self) (trade-price
trade) (or (^last-move) "")))))
;; --- index ---------------------------------------------------
(defmodel index ()
((index-def :cell nil :initarg :index-def :initform nil :accessor
index-def)
(trading-day :cell nil :initarg :trading-day :initform nil :accessor
trading-day)
(ticker-weights :initarg :ticker-weights :accessor ticker-weights
:initform (c? (loop for (ticker-sym price weight) in (index-def self)
collecting (cons (ensure-ticker (trading-day
self) ticker-sym price -60)
;; whoa, a mid-rule to-be! (FN
ticker-weights rule)
weight))))
(state :reader state
:initform (let ((moves (make-hash-table :size 50)))
(c-formula (:lazy t) ;; do not re-compute on every
trade (see FN lazy)
(count-it :index-state-calc)
(clrhash moves) ;; Re-use OK since fresh cons
triggers dataflow (FN state rule)
(let ((minutes (loop for (ticker . nil) in
(ticker-weights self)
maximizing (ticker-trade-minute
ticker))))
(without-c-dependency ;; dependency on trade minute
suffices (see FN without-c-dependency)
(loop for (ticker . weight) in (ticker-weights self)
summing (* weight (ticker-price ticker)) into
value
do (setf (gethash (ticker-sym ticker) moves)
(last-move ticker))
finally (return (list minutes value moves))))))))
(value :reader value :initform (c? (second (^state))))
;;
;; allows dependency on just value, which will not change on
unchanged trades (FN value cell)
))
(defun index-minutes (index) (first (state index)))
(defun index-moves (index) (third (state index)))
(defun index-ticker-sym-move (index ticker-sym) (gethash ticker-sym
(index-moves index)))
(defun index-ticker-move (index ticker) (index-ticker-sym-move index
(ticker-sym ticker)))
(def-c-output value ((self index))
(when *trc-trades*
(trc "index time:" (index-minutes self) :value new-value :was
old-value)))
;;; --- trade
---------------------------------------------------------------------
(defstruct trade minute ticker-sym price)
(defun message-to-trade (message)
(destructuring-bind (ticker-sym ticker-min &key last) (rest message)
(make-trade
:ticker-sym ticker-sym
:minute ticker-min
:price last)))
;;; --- utilities ---------------------------------------------------------
(defun encode-julian-date (year julian)
(+ (encode-universal-time 0 0 0 1 1 year )
(* (1- julian) 86400))) ;; seconds in a day
;; I am sorry, that is all there is to tell. So we have a mindless main
loop and a few declarations
;; and somehow we get all the functionality desired. [OK, granted, this
is a pretty simple
;; batch process which would not be too complicated in non-Cells form.
In that regard, it
;; is a good tutorial use case but does not show off Cells very much.]
Anyway...
;;
;; It occurs to me that the above notes do not convey how the damn thing
works. So let us walk
;; thru a hand-execution of the above sample data.
;;
;; (make-be 'trading-day) -> (to-be (make-instance 'trading-day))
;;
;; Each ruled Cell gets evaluated. Each Cell slot -- constant, input, or
ruled -- is output.
;; So with trading-day:
;;
;; message is input, and has no associated output function
;;
;; date is evaluated:
;;; (or .cache
;;; (when (eql :date (car (^message)))
;;; (destructuring-bind (&key date weekday)
;;; (^message)
;;; (declare (ignore weekday)) ;; derive from date
;;; (encode-julian-date (+ 2000 (floor date 1000)) (mod date
1000)))))
;;
;; .cache is nil, but so is (message self). NIL is returned, there
is no output.
;; date now has a dependency on message.
;;
;; weekday is evaluated
;;; (c? (when (^date)
;;; (multiple-value-bind (second minute hour date
month year day daylight-p zone)
;;; (decode-universal-time (^date))
;;; (declare (ignorable second minute hour date
month year daylight-p zone))
;;; day))))
;; date is nil, so weekday is NIL but has a dependency on date. No
output is defined.
;;
;; trade is evaluated
;;; (c? (when (eql :trade (car (^message)))
;;; (message-to-trade (^message)))))
;; message is NIL, so NIL is returned. trade now has a dependency
on message. The output
;; method on trade is invoked, but has no interest in NIL new values.
;;
;; indexes is evaluated:
;;; (with-c-cache ('cons)
;;; (when (eql :index (car (^message)))
;;; (make-be 'index
;;; :trading-day self
;;; :index-def (second (^message)))))))
;; message is NIL, so NIL is returned, a dependency on message
created. No output defined.
;;
;; (setf (message t-day) <the :date message>)
;;
;; Many rules are dispatched: date, trade, and indexes. Only date
processes :date messages.
;; it returns a converted date, and still has a dependency on message.
Weekday has a dependency
;; on date, so that rule gets dispatched. It returns a weekday
calculated off the date, and
;; keeps the dependency on that. Other rules return
;; NIL, which is the same value they had before. Nothing else is done
(and in this case, that
;; would only have been to call the output method on trade.
;;
;; (setf (message t-day) <the :index message>)
;;
;; The date rule runs and returns its .cache without accessing any
cell. The Cell internals
;; optimize away the fact that date ever had a rule or any kind of
cell. It sees weekday
;; was a dependent on date and nothing else, so it optimizes that away,
too. Slots end up
;; with the last values calculated, and now look to other rules as if
they were constant
;; all along.
;;
;; The trade rule runs and comes up empty again. The indexes rule runs
and adds a new
;; index list to its current contents, which happens to be NIL.
;;
;;;; make-be is called on the index instance. Each slot gets processed
in turn in a
;;;; fashion similar to that for trading-day. When the ticker-weights
rule runs, ticker
;;;; instances for each ticker in the index are created and passed to
TO-BE, in the
;;;; function ensure-ticker. No dependencies are created since
index-def is not a Cell,
;;;; so the ticker-weights cell gets optimized away.
;;;;
;;;; as each ticker is created and processed by TO-BE:
;;;;;;;
;;;; the state rule is evaluated and computes an initial index state
off the data
;;;; provided in the index-def. state ends up with dependencies on each
ticker in the
;;;; index.
;; [rest under construction]
;;
;;;
=============================================================================
;;; Footnotes
;;;
=============================================================================
;
;; --- FN to-be --------------------------------------
;; TO-BE jumpstarts a Cells instance into the flow. Literally, as in
;; the dataflow. It evaluates ruled slots to establish dependencies (those
;; get established during evaluation) and in turn arrange for state
change
;; within the model to propagate to the instance's ruled Cells. It also
;; DEF-C-OUTPUTs all cell slots so the outside world is consistent
;; with the model state. More on def-c-output below.
;
;; --- FN c-input ------------------------------------
;;
;; c-in is short for c-input, which simply means imperative application code
;; can SETF this slot. (Note that this is just the initform for this slot,
;; which can be overridden by subclasses or at make-instance time, and if
;; the override is not another C-IN or C-INPUT, then all bets are off.
ie, The
;; SETF ability depends on the type of Cell (if any) associated at run-time
;; with the slot of an instance. It
;; is not an attribute of the slot as with the :cell slot option
discussed just below.
;;
;; Anyway, C-IN lets us make a lot of points about Cells.
;;
;; First, no model is
;; an island; the dataflow has to start somewhere. Just as a VisiCalc
spreadsheet
;; has cells where you can type, say, different interest rates to see
how that
;; effects the rest of a financial model, a Cell-based application model
needs
;; some way to interface with the outside world, if only the mouse and
keyboard
;; of a GUI application.
;;
;; The way we do that is by having conventional application code feed
(SETF) data into
;; the dataflow model at what we call cell inputs. In a typical GUI app,
this means
;; having callbacks registered with the window manager. The callbacks
then take their
;; arguments (window events such as mouse-downs and key-presses) and
setf that
;; info to slots of a window or system instance modelling the window or
operating
;; system, slots mediated by c-input Cells.
;;
;; In this simple use case we have just one stream of external inputs
(messages
;; from some financial data service) being SETFed into one slot, the message
;; slot of an instance of the trading-day class.
;;
;; Second, the Cells design enforces discipline. So in case you are
;; wondering, no, if you do not bind a C-INPUT to a slot of an instance,
you cannot
;; SETF that slot from imperative code. (Aside: (SETF SLOT-VALUE) /is/ a
back door
;; allowing you to wreak havoc on your dataflow model if you so choose
(but it will
;; wreak havoc).)
;;
;; Third, you might wonder why slots meant as inputs cannot just have no
Cell at all
;; associated with them at run-time, and then have the Cell internals
accept that
;; as a SETF-able state. Well, it is a long story, but it turns out that
a lot of
;; Cells overhead can be avoided if we distinguish a slot whose value
will never
;; change from an input slot which will be SETF'ed. A simple example of
a constant
;; slot would be the bounding rectangle of a push button. Those values
have to be
;; Cells because in other graphical elements sharing the same
superclass, the bounding
;; rectangle changes. A good example is the win32-style scroll bar
thumb, which changes
;; size to reflect how much of the total file is visible. Anyway, it
turns out that
;; a significant performance boost comes from having Cells which happen
to access
;; a constant value not record a dependency on that value and, where a
rule evaluation
;; turns out not to access any non-constant other Cell slot, likewise
convert the ruled
;; slot into a constant slot. Sorry you asked?
;;
;; --- FN ephemeral
-----------------------------------------------------------
;;
;; Whoa, here is an advanced topic. Ephemeral means "fleeting". Before
getting into
;; that, the other options for the :cell option are T and NIL. T is the
default.
;; NIL means you get a normal slot having nothing to do with Cells. Now
about
;; that :ephemeral option: Messages are
;; like events: they happen, then they are no more. This is a problem for
;; Cells, which like a VisiCalc spreadsheet model (say, your household
budget)
;; is all about steady-state occasionally perturbed by inputs. That is
vague.
;; Here is a concrete example: suppose you have some game where the user has
;; to press a key when two randomly moving shapes overlap. You will have
a hit rule
;; that says (abbreviated somewhat):
;;
;; (and (eql (event *sys*) :keypress) (shapes-overlap-p *sys*))
;;
;; OK, the key is pressed but the shapes do not overlap. No cigar. Now a few
;; seconds later the shapes do overlap. The key is not being pressed,
but the
;; EVENT slot of the *sys* instance (modelling the computer system) still
;; says :keypress. bad news. Obviously we need to process an event and then
;; clear the value before processing any other model input. Now perhaps
we could
;; simply have imperative code which says:
;;
;; (setf (event *sys*) :keypress)
;; (setf (event *sys*) nil)
;;
;; But that is different. That suggests an application semantic in which the
;; EVENT slot changes from :keypress to NIL. It will trigger all the usual
;; dataflow, to see if the model should react. But in fact what we /really/
;; need is /not/ to clear the EVENT slot. What we really need is
;; ephemeral SETF behavior from a mechanism designed for steady-state.
;; We need the EVENT slot to take on a value just long enough to perturb our
;; model and then cease to be without fanfare.
;;
;; So we extend the Cells model with the :ephemeral option on a slot,
and have
;; Cell internals watch out for that and silently clear the slot once a
value
;; has been propagated to other Cells and output (again, outputs
;; are discussed below.)
;;
;; A final newbie note: watch the bouncing options. Ephemerality is a
slot option,
;; not something one tailors to the instance. Think about it. Think
about the
;; slot names. "message", "event". We want to get ephemeral behavior for
these
;; slots no matter what cell (input or ruled) we choose to associate
with them.
;; So it is more convenient and reliable to endow the slot itself with
ephemerality.
;; in other cases we see different instances enjoying different Cell-ish
qualities
;; for the same slot, sometimes constant, sometimes computed, sometimes
being
;; SETFed by imperative code outside the dataflow model. These
variations are
;; then found in the type of runtime Cell associated with the Cell slot.
;;
;; --- FN date/.cache --------------------------------------------------
;;
;;
;; There is a lot going on here, too, including some premature optimization.
;;
;; First of all, .cache is just a local variable, bound by the expansion
;; of the C? macro to the latest value calculated for this rule. It
starts out as NIL, so
;; the rule next reads the message slot of the same trading-day
instance. How so?
;;
;; ^message is a macro written by the defmodel macro. It expands simply to:
;;
;; (message self)
;;
;; It used to expand to more, including vital Cell plumbing. Now I keep
it around just
;; because I love that self-documenting quality. And yes, I have adopted
the
;; Smalltalk "self" convention over the C++ "this" convention. There is
no need
;; to use these (^macros), just code (<slot-name> self) and you will
establish a
;; dependency on the message slot. What does dependency mean?
;;
;; Simply that the next time the message slot changes (the default test
between old and
;; new values is EQL, but can be overridden), the Cells engine will
immediately kick
;; the DATE rule to see if it wants to compute a different value.
;;
;; A very important point is that dependencies are established
automatically simply
;; by invoking the reader or accessor associated with a slot, and that
this happens
;; dynamically at run-time, not by inspection of code. A second point is
that the
;; dependency is established even if the read takes place in a called
function.
;;
;; There is a backdoor. No dependencies are established in code wrapped by
;; the macro WITHOUT-C-DEPENDENCY.
;;
;; Another important point is that dependencies are re-decided
completely each time
;; a rule is invoked. So this particular rule is an oddball: it will
produce only one value, when a :date
;; message is received
;; and teh first non-NIL value is returned. On the next message (of any
kind) .cache will be
;; non-NIL and the rule will simply return that value.
;; During this last evaluation the cell will not access, hence no longer
;; depend on, the message slot or any other slot and it will get
optimized away. This
;; improves performance, since the message slot no longer bothers
propagating to
;; the date slot and Cell internals no longer have to invoke the rule.
Otherwise, every
;; new message for the entire day (none of which would be :date
messages) would kick
;; off this rule.
;;
;; --- FN with-c-cache ------------------------------------
;;
;; I am actually doing something new here. The idea is that again we deviate
;; slightly from the spreadsheet paradigm and want to accumulate data
;; from a stream of ephemeral values. Normally we calculate a slot value in
;; its entirety from data at hand, even if only ephemerally. Here we want
;; to add a newly computed result to a list of prior such results.
;;
;; with-c-cache will accept any two-argument function, and when the enclosed
;; form returns a non-nil value, pass that and the .cache to the specified
;; function.
;;
;; --- FN def-c-output --------------------------------------------
;;
;; Above is another optimization, and the long-awaited discussion of Cell
;; output.
;;
;; Output reinforces the "no model is an island" theme. We create
;; models to obtain interesting outputs from inputs, where the model
;; provides the interest. For a RoboCup player simulation, the inputs are
;; sensory information about the game, provided in a stream from a server
;; application managing multiple client players and coaches. The outputs are
;; messages to the server indicating player choices about turning, running,
;; and kicking. In between, the game play model is supposed to compute
;; actions producing more or less capable soccer play.
;;
;; --- FN trade setf optimization ---------------------------------------
;
;; But this is strange "output". It actually changes internal model state.
;; It is no output at all, just feeding dataflow back into a different
;; model input. Whassup?
;;
;; Like I said, it is an optimization. A ticker instance could have a
;; rule which watched the message stream looking for trades on that ticker,
;; but then every ticker would be watching the message stream.
;;
;; Instead, we simply leverage an "output" method to procedurally decide
which
;; ticker has been traded and directly add the trade to that ticker's list
;; of trades.
;;
;; --- FN trades def-c-output --------------------------------------
;;
;; Now the above is a proper output. Merely a print trace to standard
output, but
;; that happens to be all the output we want just now. In a real trading
application,
;; there probably would not be an output on this slot. Some gui widget
might "output"
;; by telling the OS to redraw it, or some trader instance might decide
to output
;; a buy order to an exchange, but that is about it.
;;
;; --- FN ticker-weights rule --------------------------------------
;;
;; A curiosity here is that ensure-ticker will often be making and
to-be-ing new model
;; instances while this rule is running. No problem, though it would be
possible to
;; get into trouble if such destructive (well, constructive) operations
triggered
;; dataflow back to this same rule. Here we are safe; it does not. In
fact...
;;
;; This rule runs once and then gets optimized away, because in this
simple case
;; index-def is a constant, not even a cell. Should we someday want to
handle
;; changes to an index during a trading-day, this would have to change.
;;
;; --- FN lazy ------------------------------------------------------
;;
;; Lazy ruled cells do not get calculated until someone asks their
value,
;; and once they are evaluated and dependencies have been established,
;; they merely will be flagged "obsolete" should any of those
dependencies
;; change in value.
;;
;; --- FN state rule ------------------------------------------------
;;
;; c? ends up wrapping its body in a lambda form which becomes the rule
for this
;; slot, and here that lambda form will close over the MOVES hash-table.
Neat, eh?
;; What is going on is that we do not anticipate in the application
design that
;; any cell will depend in isolation on the move of one ticker in the
index. So
;; we can allocate just one hashtable at make-instance time and reuse
that each
;; time the rule gets evaluated. Cells depending on the state Cell will know
;; when that aggregate value gets recomputed because the finally clause
conses
;; up a new list each time.
;;
;; --- FN without-c-dependency -------------------------------------
;;
;; [to be written]
;;
;; --- FN value Cell --------------------------------------------------
;;
;; Weird, right? Well, we noticed that many trades came thru at the same
price
;; sequentially. The rule above for STATE gets kicked off on each trade,
and the
;; index gets recomputed. Because it is an aggregate, we get a new list
for state
;; even if the trade was at an unchanged priced and the index value does
not change.
;;
;; Now suppose there was some BUY! rule which cared only about the index
value, and not
;; the latest minute traded of that value, which /would/ change if a new
trade at
;; an unchanged price were received. Because a new list gets consed up
(never mind the
;; new trade minute), The BUY! rule would get kicked off because of the
new list in the
;; the STATE slot. Not even overriding the default EQL test with EQUAL
would work,
;; because the trade minute would have changed.
;;
;; What to do? The above. Let VALUE get recalculated unnecessarily and
return unchanged,
;; then code the BUY! rule to use VALUE. VALUE will get kicked off, but
not BUY!, which
;; would likely be computationally intense.
;;
#| TRADEDATA
(:date 5123 :weekday 3)
(:index ((AA 29.30 7.3894672) (AIG 53.30 7.3894672)(AXP 53.00 7.3894672)
(BA 59.87 7.3894672) (C 46.80 7.3894672) (CAT 87.58 7.3894672) (DD 47.74
7.3894672)
(DIS 26.25 7.3894672) (GE 36.10 7.3894672) (GM 27.77 7.3894672) (HD
36.75 7.3894672)
(HON 35.30 7.3894672) (HPQ 21.00 7.3894672) (IBM 76.47 7.3894672)
(INTC 23.75 7.3894672) (JNJ 68.73 7.3894672) (JPM 35.50 7.3894672) (KO
43.76 7.3894672)
(MCD 29.80 7.3894672) (MMM 76.76 7.3894672) (MO 65.99 7.3894672) (MRK
34.42 7.3894672)
(MSFT 25.36 7.3894672) (PFE 27.5 7.3894672) (PG 54.90 7.3894672) (SBC
23.8 7.3894672)
(UTX 100.96 7.3894672) (VZ 36.75 7.3894672) (WMT 48.40 7.3894672) (XOM
56.50 7.3894672)))
(:trade INTC 0.001932 :last 23.75)
(:trade MSFT 0.001932 :last 25.36)
(:trade INTC 0.011931 :last 23.75)
(:trade MSFT 0.011931 :last 25.36)
(:trade MSFT 0.041965 :last 25.32)
(:trade UTX 0.067027 :last 101.39)
(:trade INTC 0.067062 :last 23.82)
(:trade MSFT 0.070397 :last 25.37)
(:trade INTC 0.070397 :last 23.82)
(:trade MSFT 0.074167 :last 25.32)
(:trade INTC 0.081800 :last 23.83)
(:trade MSFT 0.097178 :last 25.33)
(:trade MSFT 0.106488 :last 25.32)
(:trade INTC 0.110410 :last 23.82)
(:trade INTC 0.124263 :last 23.83)
(:trade MSFT 0.130411 :last 25.33)
(:trade INTC 0.143792 :last 23.81)
(:trade MSFT 0.143792 :last 25.33)
(:trade DIS 0.150441 :last 26.25)
(:trade INTC 0.160480 :last 23.82)
(:trade MSFT 0.160480 :last 25.33)
(:trade HPQ 0.166767 :last 21.00)
(:trade INTC 0.178832 :last 23.82)
(:trade MSFT 0.183710 :last 25.33)
(:trade DIS 0.187167 :last 26.25)
(:trade AIG 0.193117 :last 53.60)
(:trade INTC 0.196399 :last 23.81)
(:trade PFE 0.200523 :last 27.51)
(:trade MSFT 0.200523 :last 25.33)
(:trade GE 0.202185 :last 36.11)
(:trade MSFT 0.207199 :last 25.37)
(:trade BA 0.209810 :last 59.75)
(:trade INTC 0.210524 :last 23.83)
(:trade MSFT 0.230556 :last 25.37)
(:trade INTC 0.230556 :last 23.83)
(:trade BA 0.234812 :last 59.76)
(:trade MSFT 0.240580 :last 25.37)
(:trade INTC 0.247233 :last 23.83)
(:trade MSFT 0.256892 :last 25.37)
(:trade UTX 0.257729 :last 101.33)
(:trade GE 0.261942 :last 36.11)
(:trade AIG 0.267072 :last 53.60)
(:trade MSFT 0.272956 :last 25.36)
(:trade INTC 0.275617 :last 23.83)
(:trade WMT 0.280660 :last 48.40)
(:trade SBC 0.284975 :last 23.78)
(:trade GE 0.289229 :last 36.10)
(:trade MSFT 0.292285 :last 25.35)
(:trade DIS 0.295646 :last 26.30)
(:trade HPQ 0.303630 :last 21.04)
(:trade IBM 0.305629 :last 76.60)
(:trade INTC 0.307321 :last 23.81)
(:trade INTC 0.310671 :last 23.81)
(:trade SBC 0.316331 :last 23.76)
(:trade AIG 0.322292 :last 53.60)
(:trade MSFT 0.324057 :last 25.36)
(:trade MCD 0.324057 :last 29.79)
(:trade UTX 0.325694 :last 101.15)
(:trade INTC 0.327348 :last 23.81)
(:trade IBM 0.336878 :last 76.60)
(:trade MSFT 0.342414 :last 25.37)
(:trade MSFT 0.345710 :last 25.37)
(:trade HD 0.346983 :last 36.82)
(:trade BA 0.347295 :last 59.80)
(:trade MCD 0.360765 :last 29.80)
(:trade HPQ 0.364067 :last 21.03)
(:trade MSFT 0.364067 :last 25.37)
(:trade SBC 0.367409 :last 23.79)
(:trade MSFT 0.392928 :last 25.36)
(:trade AIG 0.407453 :last 53.55)
(:trade HPQ 0.407533 :last 21.03)
(:trade SBC 0.407533 :last 23.79)
(:trade MSFT 0.407533 :last 25.36)
(:trade INTC 0.407533 :last 23.82)
(:trade HPQ 0.407533 :last 21.03)
(:trade HD 0.407545 :last 36.84)
(:trade BA 0.413185 :last 59.80)
(:trade INTC 0.414117 :last 23.81)
(:trade PFE 0.420796 :last 27.51)
(:trade DIS 0.424120 :last 26.30)
(:trade AIG 0.424654 :last 53.58)
(:trade INTC 0.427471 :last 23.81)
(:trade XOM 0.429865 :last 56.85)
(:trade IBM 0.431927 :last 76.65)
(:trade HPQ 0.432407 :last 21.04)
(:trade HD 0.432507 :last 36.84)
(:trade MCD 0.439207 :last 29.80)
(:trade MSFT 0.442518 :last 25.36)
(:trade DIS 0.442518 :last 26.30)
(:trade MSFT 0.453747 :last 25.36)
(:trade PFE 0.458821 :last 27.52)
(:trade IBM 0.459026 :last 76.66)
(:trade HON 0.467342 :last 35.36)
(:trade XOM 0.469083 :last 56.88)
(:trade INTC 0.470871 :last 23.80)
(:trade SBC 0.476712 :last 23.79)
(:trade BA 0.476730 :last 59.80)
(:trade MCD 0.479248 :last 29.80)
(:trade HPQ 0.479248 :last 21.03)
(:trade AIG 0.480883 :last 53.57)
(:trade MSFT 0.482567 :last 25.36)
(:trade INTC 0.482567 :last 23.80)
(:trade IBM 0.484223 :last 76.73)
(:trade MSFT 0.494243 :last 25.36)
(:trade AIG 0.497551 :last 53.57)
(:trade PFE 0.497569 :last 27.53)
(:trade INTC 0.504245 :last 23.80)
(:trade HD 0.504660 :last 36.84)
(:trade IBM 0.504849 :last 76.73)
(:trade GM 0.507621 :last 30.53)
(:trade SBC 0.511484 :last 23.79)
(:trade HPQ 0.514265 :last 21.04)
(:trade HD 0.514798 :last 36.85)
(:trade MSFT 0.517601 :last 25.32)
(:trade WMT 0.524286 :last 48.46)
(:trade IBM 0.524286 :last 76.74)
(:trade INTC 0.529220 :last 23.80)
(:trade HPQ 0.536813 :last 21.04)
(:trade PG 0.537627 :last 54.91)
(:trade PFE 0.540979 :last 27.54)
(:trade INTC 0.544290 :last 23.80)
(:trade PG 0.547549 :last 54.91)
(:trade XOM 0.547624 :last 56.85)
(:trade HON 0.547687 :last 35.40)
(:trade UTX 0.550986 :last 101.33)
(:trade HD 0.555694 :last 36.85)
(:trade MSFT 0.560792 :last 25.35)
(:trade INTC 0.564337 :last 23.80)
(:trade XOM 0.566779 :last 56.85)
(:trade BA 0.567359 :last 59.81)
(:trade HON 0.581023 :last 35.41)
(:trade INTC 0.589796 :last 23.80)
(:trade BA 0.596050 :last 59.80)
(:trade CAT 0.612134 :last 87.83)
(:trade WMT 0.618386 :last 48.44)
(:trade INTC 0.620474 :last 23.80)
(:trade MCD 0.624417 :last 29.80)
(:trade MSFT 0.627748 :last 25.35)
(:trade BA 0.630881 :last 59.83)
(:trade AIG 0.634410 :last 53.56)
(:trade MCD 0.637785 :last 29.79)
(:trade HON 0.637785 :last 35.40)
(:trade INTC 0.649577 :last 23.79)
(:trade BA 0.655889 :last 59.85)
(:trade HD 0.662287 :last 36.83)
(:trade AIG 0.669431 :last 53.53)
(:trade HON 0.671133 :last 35.44)
(:trade MCD 0.674457 :last 29.79)
(:trade MO 0.683443 :last 66.20)
(:trade INTC 0.687668 :last 23.79)
(:trade MSFT 0.691181 :last 25.35)
(:trade PFE 0.694477 :last 27.54)
(:trade MSFT 0.720936 :last 25.35)
(:trade GM 0.726237 :last 30.50)
(:trade WMT 0.730056 :last 48.40)
(:trade IBM 0.740544 :last 76.74)
(:trade PG 0.744569 :last 54.91)
(:trade HON 0.752103 :last 35.46)
(:trade CAT 0.753014 :last 87.85)
(:trade MO 0.763918 :last 66.20)
(:trade MSFT 0.764592 :last 25.35)
(:trade HON 0.771289 :last 35.46)
(:trade BA 0.772935 :last 59.75)
(:trade JPM 0.773229 :last 35.51)
(:trade MSFT 0.774612 :last 25.35)
(:trade PG 0.776267 :last 54.91)
(:trade AIG 0.781168 :last 53.54)
(:trade HD 0.782946 :last 36.87)
(:trade CAT 0.784614 :last 87.85)
(:trade XOM 0.786285 :last 56.88)
(:trade MSFT 0.792950 :last 25.36)
(:trade UTX 0.794689 :last 101.40)
(:trade INTC 0.797969 :last 23.78)
(:trade IBM 0.801301 :last 76.74)
(:trade HD 0.809652 :last 36.87)
(:trade JPM 0.809652 :last 35.51)
(:trade MSFT 0.811489 :last 25.37)
(:trade MO 0.812994 :last 66.20)
(:trade IBM 0.816563 :last 76.75)
(:trade MCD 0.828046 :last 29.77)
(:trade UTX 0.829055 :last 101.37)
(:trade MSFT 0.833420 :last 25.36)
(:trade GM 0.837650 :last 30.50)
(:trade IBM 0.838004 :last 76.75)
(:trade HON 0.838531 :last 35.47)
(:trade XOM 0.841372 :last 56.88)
(:trade MCD 0.841894 :last 29.78)
(:trade KO 0.853202 :last 43.98)
(:trade UTX 0.858235 :last 101.38)
(:trade INTC 0.864331 :last 23.82)
(:trade PFE 0.869104 :last 27.55)
(:trade HON 0.873063 :last 35.48)
(:trade IBM 0.873095 :last 76.77)
(:trade HD 0.873132 :last 36.87)
(:trade XOM 0.884796 :last 56.86)
(:trade UTX 0.884820 :last 101.38)
(:trade HON 0.888886 :last 35.48)
(:trade INTC 0.891420 :last 23.81)
(:trade CAT 0.895715 :last 87.86)
(:trade MO 0.898111 :last 66.19)
(:trade XOM 0.898111 :last 56.87)
(:trade IBM 0.899775 :last 76.78)
(:trade BA 0.899775 :last 59.83)
(:trade MSFT 0.901469 :last 25.38)
(:trade HD 0.906673 :last 36.86)
(:trade HPQ 0.908113 :last 21.03)
(:trade CAT 0.916467 :last 87.85)
(:trade BA 0.916467 :last 59.83)
(:trade MSFT 0.918773 :last 25.38)
(:trade PFE 0.926271 :last 27.57)
(:trade MO 0.926288 :last 66.18)
(:trade WMT 0.929791 :last 48.40)
(:trade KO 0.932333 :last 43.98)
(:trade JNJ 0.933224 :last 68.15)
(:trade PG 0.936516 :last 54.91)
(:trade INTC 0.938989 :last 23.81)
(:trade IBM 0.942596 :last 76.78)
(:trade XOM 0.944052 :last 56.89)
(:trade INTC 0.944885 :last 23.81)
(:trade BA 0.946486 :last 59.85)
(:trade IBM 0.958178 :last 76.78)
(:trade INTC 0.959853 :last 23.81)
(:trade JPM 0.959897 :last 35.50)
(:trade WMT 0.961498 :last 48.40)
(:trade MCD 0.963195 :last 29.77)
(:trade HPQ 0.966525 :last 21.03)
(:trade AIG 0.968663 :last 53.54)
(:trade XOM 0.978210 :last 56.89)
(:trade AIG 0.979896 :last 53.55)
(:trade CAT 0.979896 :last 87.85)
(:trade MCD 0.984732 :last 29.77)
(:trade PG 0.985307 :last 54.90)
(:trade WMT 0.995716 :last 48.41)
(:trade MSFT 1.005256 :last 25.38)
(:trade PFE 1.005256 :last 27.55)
(:trade JPM 1.008448 :last 35.48)
(:trade CAT 1.011343 :last 87.86)
(:trade XOM 1.011825 :last 56.88)
(:trade INTC 1.012667 :last 23.79)
(:trade JNJ 1.018655 :last 68.15)
(:trade KO 1.021589 :last 43.99)
(:trade INTC 1.026597 :last 23.78)
(:trade HD 1.029577 :last 36.85)
(:trade MSFT 1.029936 :last 25.39)
(:trade JPM 1.033267 :last 35.49)
(:trade C 1.064996 :last 46.80)
(:trade CAT 1.065946 :last 87.85)
(:trade MCD 1.066687 :last 29.75)
(:trade MRK 1.066687 :last 34.33)
(:trade PFE 1.066687 :last 27.55)
(:trade INTC 1.066687 :last 23.79)
(:trade INTC 1.066687 :last 23.79)
(:trade XOM 1.068360 :last 56.88)
(:trade JPM 1.068360 :last 35.49)
(:trade XOM 1.068360 :last 56.89)
(:trade KO 1.068360 :last 43.99)
(:trade MRK 1.070274 :last 34.34)
(:trade HON 1.073312 :last 35.49)
(:trade PFE 1.080025 :last 27.55)
(:trade MCD 1.080025 :last 29.75)
(:trade INTC 1.080025 :last 23.79)
(:trade AIG 1.083337 :last 53.55)
(:trade GM 1.083420 :last 30.55)
(:trade XOM 1.086739 :last 56.89)
(:trade HON 1.093425 :last 35.49)
(:trade HPQ 1.093425 :last 21.03)
(:trade INTC 1.093425 :last 23.79)
(:trade MSFT 1.093425 :last 25.37)
(:trade JPM 1.098339 :last 35.49)
(:trade IBM 1.099113 :last 76.86)
(:trade XOM 1.104257 :last 56.89)
(:trade MCD 1.104268 :last 29.74)
(:trade GE 1.108379 :last 36.14)
(:trade MSFT 1.108408 :last 25.40)
(:trade XOM 1.115052 :last 56.89)
(:trade JPM 1.118397 :last 35.50)
(:trade GM 1.118397 :last 30.55)
(:trade C 1.125426 :last 46.78)
(:trade MCD 1.132390 :last 29.74)
(:trade WMT 1.133494 :last 48.40)
(:trade MRK 1.135099 :last 34.33)
(:trade MSFT 1.135099 :last 25.39)
(:trade INTC 1.135099 :last 23.78)
(:trade INTC 1.146096 :last 23.79)
(:trade KO 1.146108 :last 43.99)
(:trade WMT 1.155346 :last 48.41)
(:trade PG 1.158447 :last 54.90)
(:trade WMT 1.162645 :last 48.41)
(:trade HON 1.162660 :last 35.52)
(:trade KO 1.162672 :last 43.98)
(:trade JNJ 1.166783 :last 68.20)
(:trade DIS 1.166815 :last 26.34)
(:trade HD 1.166856 :last 36.90)
(:trade MCD 1.171129 :last 29.74)
(:trade INTC 1.175130 :last 23.79)
(:trade JPM 1.178485 :last 35.50)
(:trade KO 1.178485 :last 43.98)
(:trade MSFT 1.184447 :last 25.39)
(:trade AIG 1.191811 :last 53.56)
(:trade WMT 1.195138 :last 48.41)
(:trade MSFT 1.199050 :last 25.39)
(:trade MO 1.201440 :last 66.18)
(:trade INTC 1.201841 :last 23.80)
(:trade DIS 1.201841 :last 26.34)
(:trade JNJ 1.202292 :last 68.20)
(:trade C 1.205172 :last 46.79)
(:trade KO 1.205172 :last 43.98)
(:trade WMT 1.209557 :last 48.40)
(:trade INTC 1.209927 :last 23.79)
(:trade VZ 1.209962 :last 34.75)
(:trade MSFT 1.213558 :last 25.37)
(:trade C 1.220169 :last 46.79)
(:trade DIS 1.220225 :last 26.34)
(:trade PFE 1.220225 :last 27.55)
(:trade JNJ 1.220921 :last 68.20)
(:trade MMM 1.223614 :last 76.70)
(:trade INTC 1.226875 :last 23.79)
(:trade DIS 1.230230 :last 26.34)
(:trade HPQ 1.230230 :last 21.03)
(:trade HON 1.230230 :last 35.52)
(:trade PFE 1.230230 :last 27.56)
(:trade SBC 1.230230 :last 23.78)
(:trade C 1.236915 :last 46.79)
(:trade MSFT 1.240577 :last 25.40)
(:trade DIS 1.243960 :last 26.34)
(:trade SBC 1.250258 :last 23.78)
(:trade MCD 1.250258 :last 29.74)
(:trade MSFT 1.250258 :last 25.40)
(:trade INTC 1.253588 :last 23.79)
(:trade HON 1.253588 :last 35.53)
(:trade MCD 1.257704 :last 29.74)
(:trade MSFT 1.262803 :last 25.37)
(:trade KO 1.271926 :last 43.99)
(:trade JPM 1.271926 :last 35.51)
(:trade VZ 1.276339 :last 34.75)
(:trade MSFT 1.280283 :last 25.40)
(:trade HPQ 1.280283 :last 21.03)
(:trade DIS 1.288624 :last 26.34)
(:trade GE 1.288664 :last 36.14)
(:trade JPM 1.288664 :last 35.51)
(:trade AIG 1.290300 :last 53.59)
(:trade CAT 1.290300 :last 87.86)
(:trade IBM 1.290300 :last 76.85)
(:trade SBC 1.291940 :last 23.77)
(:trade XOM 1.301948 :last 56.88)
(:trade DIS 1.303625 :last 26.34)
(:trade AIG 1.304047 :last 53.60)
(:trade KO 1.305316 :last 43.99)
(:trade JPM 1.305316 :last 35.51)
(:trade C 1.305316 :last 46.79)
(:trade KO 1.314761 :last 43.99)
(:trade DIS 1.316972 :last 26.35)
(:trade HON 1.316972 :last 35.54)
(:trade CAT 1.317022 :last 87.86)
(:trade IBM 1.317022 :last 76.85)
(:trade GE 1.318640 :last 36.15)
(:trade WMT 1.320354 :last 48.41)
(:trade HPQ 1.322354 :last 21.04)
(:trade AIG 1.331152 :last 53.59)
(:close)
|#
(defun msg-start (m)
(search "TRADEDATA" m))
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