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Club Amiga de Montreal - CAM
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018.lha
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examples
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sim2.st
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1986-10-19
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"
Simple Minded simulation from Chapter 6 of book
IceCream Store -
single event queue
multiple group size
discrete probability on number of scoops selected
"
Class Main
[
main | i |
i <- IceCreamStore new.
[i time < 25] whileTrue: [ i proceed ].
i reportProfits
]
Class Simulation
| currentTime nextEvent nextEventTime |
[
new
currentTime <- 0
|
time
^ currentTime
|
addEvent: event at: eventTime
nextEvent <- event.
nextEventTime <- eventTime
|
proceed
currentTime <- nextEventTime.
self processEvent: nextEvent
]
Class IceCreamStore :Simulation
| profit rand scoopDistribution |
[
new
profit <- 0.
rand <- Random new.
(scoopDistribution <- DiscreteProbability new)
defineWeights: #(65 25 10).
self scheduleArrival
|
scheduleArrival
self addEvent: Customer new
at: (self time + (rand randInteger: 5))
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processEvent: event
('customer received at ', self time printString) print.
profit <- profit + ((self scoopsFor: event groupSize) * 0.17 ).
self scheduleArrival
|
scoopsFor: group | number |
number <- 0.
group timesRepeat:
[number <- number + scoopDistribution next].
('group of ', group printString, ' have ', number
printString, ' scoops ') print.
^ number
|
reportProfits
('profits are ', profit printString) print
]
Class Customer
| groupSize |
[
new
groupSize <- (Random new "randomize" ) randInteger: 8
|
groupSize
^ groupSize
]
Class DiscreteProbability
| weights rand max |
[
defineWeights: anArray
weights <- anArray.
(rand <- Random new) "randomize".
max <- anArray inject: 0 into: [:x :y | x + y]
|
next | index value |
value <- rand randInteger: max.
index <- 1.
[value > (weights at: index)]
whileTrue: [value <- value - (weights at: index).
index <- index + 1].
^ index
]