Posted by Tom Moertel
Tue, 12 Sep 2006 21:30:00 GMT
I am on the planning committee for the 2006 Pittsburgh Perl
Workshop and serve as the primary point of contact for
speakers. That means I get the inside scoop on the talks.
And from what I have seen, all I can say is, These
talks kick ass. Well, actually I can say one more thing:
If there is any possible way you can manage to get yourself to Pittsburgh, Pennsylvania
on Saturday, 23 September 2006, do not wait, do not mull
it over, register now for the Pittsburgh Perl Workshop.
If you miss this one, you’ll probably end up weeping in front of your keyboard for a long, long time.
PPW ’06 has speakers from the worlds of finance,
bioinformatics, engineering, politics, health care, insurance, Web-2.0
start-ups, environmental monitoring, and mathematics. And they all
have fascinating things to share with you about how they make Perl
work for them and about how you can make Perl work for you.
Registration is only $20 – can you imagine that, in an age when
programming conferences routinely cost hundreds if not thousands of dollars? – and all of the talks show you how to use
Perl to do real work, solve real problems, and make your real life as a
programming professional a whole lot saner. Even if you think
you don’t care about Perl, you ought to be a part of
PPW ’06 just for the rare opportunity to discover something
you may have overlooked. (At $20, when are you ever going to get
a chance like this again?)
Posted in perl, pittsburgh
Tags cool, perl, pittsburgh, ppw, ppw06, stuff, talks
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Posted by Tom Moertel
Thu, 04 May 2006 02:49:00 GMT
Local supermarket chain Giant Eagle has a
brilliant marketing scheme called “fuelperks”: For every 50 dollars
you spend on groceries in their stores, you earn a one-time,
10-cent-per-gallon discount at Giant Eagle’s “GetGo” gas stations.
The discounts accumulate until you use them (or they expire in three
months). If you buy 109 dollars of groceries, for example, you will
earn a 20-cent-per-gallon gas discount. (The remaining 9 dollars will carry over to your next grocery purchase.)
What makes the scheme brilliant is that its psychological effect is
wildly in excess of the discount’s actual value. Many people will
wait in lines to buy gas from GetGo, even though the discount
provides no incentive to do so. Further, as gas prices rise, many
customers perceive the discount to be all the more valuable, even
though it is not.
I thought it would be interesting to
scrutinize the discount and answer
some common questions about it.
How much is the “fuelperks” discount worth?
The discount is typically equivalent to about 3- to 4-percent cash back on your
grocery purchases, depending on the average amount of gas you purchase
per fill-up. For example, my mid-size car has a 14-gallon tank, and I always
buy a full tank’s worth of gas, so for me the discount is about 2.8 percent:
14 gallons × 0.10 dollars/gallon / 50 dollars = 0.028
If you drive a luxury-barge SUV and can manage to buy a full 30 gallons at each fill up, you will earn the theoretical maximum discount of 6 percent.
How do I get the maximum benefit from the discount?
To get the maximum benefit, follow two simple rules:
- buy a full tank of gas whenever you use earned discounts at GetGo
- use your discounts before they expire
Do I lose benefits if I buy gas somewhere else?
No. Even if you buy most of your gas somewhere else, as long as you buy gas from GetGo frequently enough to use your
discounts before they expire, you will get the maximum benefit.
When gas prices increase, do I get more benefits?
No. The value of any discounts you have earned depend on
the quantity of gas you purchase. The price of gas
at the time of purchase has no effect on the discount.
Any other questions?
If you have any questions (or comments), please post a comment.
Posted in pittsburgh, marketing
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Posted by Tom Moertel
Fri, 28 Apr 2006 20:30:00 GMT
At last night’s
meeting
of the Pittsburgh Coding Dojo, we worked
on the Supermarket Pricing
Kata.
This particular kata was intended to be food for thought – a “shower
kata” – but our goal was to do some coding, so we made the problem
more concrete:
- Come up with a sensible way to represent common supermarket
pricing rules such as “buy one, get one free,” “three for a dollar,”
”$0.34 per ounce,” and so on
- Implement a method to check out a shopping cart full of goods,
applying all applicable pricing rules, and computing the total price
for the cart’s contents
Most people paired up, but I worked alone because I wasn’t ready to code right away. (Laptop issues.) At the end of the meeting, nobody had a working solution. (I guess it
was a shower kata for a reason.)
I had a partial solution, but I
didn’t like my internal representation of prices because it conflated
goods and their pricing rules.
Over lunch today I came up with a more
sensible representation and finished off my implementation.
Now I’m happy with it.
The code
Here’s my solution. I stripped the comments to emphasize the code
itself (a forest and trees thing). If you want to see the comments,
see the unstripped source.
module SupermarketPricing where
import Control.Arrow ((&&&))
import Data.List (groupBy, sort)
import Test.HUnit
type Portion = Double
type Count = Portion
type Price = Double
type Name = String
data PricingRule
= Per Portion Price
| For Count Price Price
deriving (Eq, Ord, Read, Show)
data Good
= G { name :: Name, quantity :: !Portion, rule :: PricingRule }
deriving (Eq, Ord, Read, Show)
per nm y x p = G nm y (Per x p)
each nm p = G nm 1 (For 1 p p)
for nm n p = G nm 1 (For n p p)
bogo = flip bngo 1
btgo = flip bngo 2
bngo nm n p = G nm 1 (For n' np p)
where (n', np) = (n + 1, p * n)
checkout :: [Good] -> Price
checkout =
checkoutBy $ sum . map price
subtotal :: [Good] -> [((Portion, Name), Price)]
subtotal =
checkoutBy $ map ((quantity &&& name) &&& price)
checkoutBy :: ([Good] -> a) -> [Good] -> a
checkoutBy f =
f . map (foldl1 combine) . groupByName . sort
where
groupByName = groupBy (\g1 g2 -> name g1 == name g2)
price :: Good -> Price
price (G nm y (Per x p)) = y * p / x
price (G nm m (For n p p2)) = (m r) * p / n + r * p2
where
r = fromIntegral $ round m `rem` round n
combine :: Good -> Good -> Good
combine g1@(G nm x rule) g2@(G nm2 x2 rule2)
| nm /= nm2 || rule /= rule2
= error $ "can't combine incompatible goods " ++ show [g1, g2]
| otherwise
= G nm (x + x2) rule
Read on for an explanation of the code and my unit tests.
Read more...
Posted in programming, haskell, pittsburgh
Tags coding, dojo, haskell, katas, pricing, supermarket
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Posted by Tom Moertel
Wed, 12 Apr 2006 16:29:00 GMT
If you live anywhere near Pittsburgh and are interested in Perl, have
I got a couple of announcements for you:
First, the ever-fascinating Mark Jason
Dominus is speaking tonight (2006-04-12, now passed) on
Improving Your Perl Code at
the regular meeting of the Pittsburgh Perl
Mongers. If you are interested in Perl,
be there. (You don’t need to be a Perl Monger to attend.) Mark is a
great speaker and wrote one of my favorite Perl books, Higher Order
Perl, which puts the fun in functional
programming.
Second, The Pittsburgh Perl Workshop is on. Put a big circle around this date on your
calendar: Saturday, 23 September 2006. It’s
a full day of sleeves-rolled-up Perl fun, all focused on the sweat-inducing theme of Perl At Work. To top it off, the Workshop is dirt cheap, especially if you get the 50-percent “Early Bird” discount. (Hint:
register now.)
It’s a fun time for Perl folks in Pittsburgh.
Update: MJD gave his talk, and it rocked. If you missed it, you should find a time machine now and use it to take yourself back to Wednesday evening to hear his talk. Or you could find out when he is speaking in the future and be there. Either way, don’t miss out again.
Posted in perl, pittsburgh
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Posted by Tom Moertel
Wed, 05 Apr 2006 19:18:00 GMT
On the WPLUG mailing list I came across a post
about the formation of a Pittsburgh Coding
Dojo. The idea is to get a bunch
of hackers together and have them work on solving a challenge
problem with the goal of sharpening their programming skills and
learning from each other.
There was a trial meeting on 31 March that focused on The Bowling Game
Kata.
The challenge was essentially to write some code that scores
a full (ten-frame) game of bowling. A game is represented by a series
of “rolls,” each being the number of pins knocked down by a
roll of the bowling ball. The scoring function must
determine frame boundaries from the sequence of rolls and score all
ten frames according to the rules of bowling, i.e., taking into account
spares and strikes and the final frame.
The challenge sounded like a fun lunch-break problem, and so I
whipped up the following solution in Haskell. (You might find
it interesting to compare this solution to the Java-based
solutions on the web.)
module Bowling (score) where
import Test.HUnit
score rs = sc 0 1 rs
sc s 11 _ = s
sc s f rs = case rs of
10:rs' -> sc' 3 rs'
x:y:rs' | x + y == 10 -> sc' 3 rs'
| otherwise -> sc' 2 rs'
_ -> error "ill-formed sequence of rolls"
where
sc' n rs' = sc (s + sum (take n rs)) (f + 1) rs'
Here are my unit tests:
tests = test
[ "gutters" ~: score (rep 20 0) ~?= 0
, "ones" ~: score (rep 20 1) ~?= 20
, "fives" ~: score (rep 22 5) ~?= 150
, "strikes" ~: score (rep 12 10) ~?= 300
, "1 + gutters" ~: score (1 : rep 19 0) ~?= 1
, "first spare" ~: score (5:5:5 : rep 17 0) ~?= 20
, "first strike" ~: score (10:5:5 : rep 17 0) ~?= 30
, "last spare" ~: rscore (5:5:5 : rep 18 0) ~?= 15
, "last strike" ~: rscore (5:5:10 : rep 18 0) ~?= 20
]
where
rep = replicate
rscore = score . reverse
If you have a little free time, code up a solution in your
favorite language.
Posted in programming, haskell, pittsburgh
Tags bowling, haskell, kata
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Posted by Tom Moertel
Tue, 31 Jan 2006 02:57:00 GMT
I love espresso. It’s my favorite way to enjoy coffee. Even so, I
almost never order espresso in coffee shops because, here in the
United States, very few coffee shops have mastered the exacting
process by which espresso is made. Dr. Josuma John of the Josuma
Coffee Company writes that
“more than 95 percent of North American espresso is poorly made, and,
in fact, undrinkable.” My experience with Pittsburgh-area coffee
shops in the last decade provides no evidence to refute Dr. John’s
claim.
If espresso in the United States is so bad, why do Americans drink
enough of it to support a Starbucks on every street corner? The reason
is that Americans drink espresso almost exclusively in the form of
milk-based beverages: cappuccinos, lattes, and mochas. Milk and
flavored syrups are the main attractions. Espresso serves only as a
coffee-flavored backdrop in which bitterness, a characteristic
of poorly made espresso, complements the abundant sweetness of milk
laced with sugar syrups. American coffee-shop owners thus have little
incentive to offer better espresso to their customers – bad espresso
is good enough.
Because of this sad reality, I have developed through hard experience
the following reliable guideline for ordering espresso at American
coffee shops: Don’t. The one exception I make is for new coffee
shops, at which I will try a double espresso, just to see what I get.
Almost always, I get a bad espresso, bitter and watery.
And that is what I had expected back in April 2005, when I spotted the
brand-new sign for Aldo Coffee Co. in my
home town of Mt. Lebanon, Pennsylvania, located in Pittsburgh’s South
Hills. I went in, dragging my wife along, and placed my order.
Then something unusual happened. The barista asked me, somewhat
hopefully it seemed, if I drank espresso regularly. When I said yes, she seemed pleased. When she followed up by
asking me if I read
alt.coffee, I was stunned.
When I observed that she was timing my shot, my brain actually shut
down for a few seconds while it forcibly recalibrated itself to
accommodate the seemingly impossible: that I was standing in a
coffee shop in my home town, conversing with a barista about
alt.coffee, and mere seconds away from receiving what was very likely
to be good espresso.
Read more...
Posted in good stuff, espresso, pittsburgh
Tags aldo, coffee, espresso, mtlebo
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Posted by Tom Moertel
Fri, 12 Aug 2005 16:00:00 GMT
Tonight’s meeting of the Pittsburgh Perl Mongers
was held at the World Headquarters of the Professional Amateur
Pinball Association to coincide with the
PAPA 8 World Pinball Championships.
To say it was a cool meeting doesn’t do it justice. Not only did we
hear a fun talk on writing CGI-contained Mason applications by our own
Dan Wright, but after the meeting
we wandered around and
played fabulous, well-maintained vintage pinball machines and fine 1980s-era video games.
And we watched the world’s best pinball players compete.
And we ate junk food. Yeah!
By all means, do look at the PAPA 8 photos. And if you need the love
that only good pinball can provide, experience PAPA 8 for yourself:
the tournament runs for the next few days.
A big thanks to PAPA for hosting us!
—Tom
Posted in perl, fun stuff, pittsburgh
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