|
Discussion of the Essence# programming language, and related issues and technologies. |
| Blog Timezone: | America/Los_Angeles [Winter: -0800 hhmm | Summer: -0700 hhmm] |
| Your local time: |
Göran Krampe has proposed (and implemented in Squeak) a generic, extensible data interchange format for Smalltalk. His initial use is limited to code delta streams, but the format actually defines a generic, extensible architecture that could be used to represent any sort of data.
I like it. I second the motion!
Most of the listed "holidays" will actually be business days, although some will not. The US Federal Holidays (on which most US Government offices will close, along with all Federally-chartered banks) are highlighted in bold. Generally, each business decides on its own which of these days (if any) will be non-business days (and for which employees):
Thu, 01 Jan 2009: NewYearsDay
Thu, 08 Jan 2009: JacksonDay
Mon, 19 Jan 2009: MartinLutherKingDay
Tue, 20 Jan 2009: InaugurationDay
Mon, 02 Feb 2009: GroundhogDay
Thu, 12 Feb 2009: LincolnsBirthday
Sat, 14 Feb 2009: ValentinesDay
Mon, 16 Feb 2009: WashingtonsBirthday
Tue, 17 Mar 2009: StPatricksDay
Wed, 01 Apr 2009: AprilFoolsDay
Fri, 10 Apr 2009: GoodFriday
Sun, 12 Apr 2009: Easter
Wed, 22 Apr 2009: EarthDay
Wed, 22 Apr 2009: AdministrativeAssistantsDay
Fri, 24 Apr 2009: ArborDay
Sun, 10 May 2009: MothersDay
Mon, 25 May 2009: MemorialDay
Sun, 14 Jun 2009: FlagDay
Sun, 21 Jun 2009: FathersDay
Sat, 04 Jul 2009: IndependenceDay
Sun, 26 Jul 2009: ParentsDay
Mon, 07 Sep 2009: LaborDay
Sun, 13 Sep 2009: GrandParentsDay
Mon, 12 Oct 2009: ColumbusDay
Sat, 24 Oct 2009: UnitedNationsDay
Sat, 31 Oct 2009: Halloween
Wed, 11 Nov 2009: VeteransDay
Thu, 26 Nov 2009: Thanksgiving
Fri, 27 Nov 2009: DayAfterThanksgiving
Thu, 24 Dec 2009: ChristmasEve
Fri, 25 Dec 2009: Christmas
Thu, 31 Dec 2009: NewYearsEve
| list |
list := SortedCollection sortBlock: [:a :b | a value < b value].
SemanticDatePolicy unitedStates
nominalAnnualEventOccurenceDatesInYear: 2009 do:
[:semanticKey :date | list add: semanticKey->date].
Transcript cr.
list do:
[:assoc |
Transcript
cr; show: (assoc value printStringUsing: #rfc2822);
show: ':'; tab; show: assoc key]
Reading a recent post by Ramon Leon, a thought occurred to me: In many cases, there's a better alternative to using #copyWithout:. The alternative would be to use #do:without:, implemeted as follows:
do: block1 without: anElementThe advantage should be obvious: It avoids making a "throw away" copy of the initial collection.
self do: [:each | each = anElement ifFalse: [block1 value: each]]
Version 2008b of the Chronos Time Zone Repository has been published. It is based on version 2008b of the Olson Time Zone Database.
Downloads:
Since it's Easter today (according to the rule for computing Easter established by Pope Gregory in the late sixteenth century,) I thought I would post the occurrence dates for Easter from 2000 to 2020 AD (Gregorian):
2000-04-23
2001-04-15
2002-03-31
2003-04-20
2004-04-11
2005-03-27
2006-04-16
2007-04-08
2008-03-23
2009-04-12
2010-04-04
2011-04-24
2012-04-08
2013-03-31
2014-04-20
2015-04-05
2016-03-27
2017-04-16
2018-04-01
2019-04-21
2020-04-12
And here's the Chronos code that computes the list above:
2000 to: 2020
do: [:year |
Transcript
cr;
show: (GregorianEaster canonical inYear: year) printString]
Version 2007k of the Chronos Time Zone Repository has been published. It is based on version 2007k of the Olson Time Zone Database.
Downloads:
Most of the listed "holidays" will actually be business days, although some will not. The US Federal Holidays (on which most US Government offices will close, along with all Federally-chartered banks) are highlighted in bold. Generally, each business decides on its own which of these days (if any) will be non-business days (and for which employees):
Tue, 01 Jan 2008: NewYearsDay
Tue, 08 Jan 2008: JacksonDay
Mon, 21 Jan 2008: MartinLutherKingDay
Sat, 02 Feb 2008: GroundhogDay
Tue, 12 Feb 2008: LincolnsBirthday
Thu, 14 Feb 2008: ValentinesDay
Mon, 18 Feb 2008: WashingtonsBirthday
Mon, 17 Mar 2008: StPatricksDay
Fri, 21 Mar 2008: GoodFriday
Sun, 23 Mar 2008: Easter
Tue, 01 Apr 2008: AprilFoolsDay
Tue, 22 Apr 2008: EarthDay
Wed, 23 Apr 2008: AdministrativeAssistantsDay
Fri, 25 Apr 2008: ArborDay
Sun, 11 May 2008: MothersDay
Mon, 26 May 2008: MemorialDay
Sat, 14 Jun 2008: FlagDay
Sun, 15 Jun 2008: FathersDay
Fri, 04 Jul 2008: IndependenceDay
Sun, 27 Jul 2008: ParentsDay
Mon, 01 Sep 2008: LaborDay
Sun, 07 Sep 2008: GrandParentsDay
Mon, 13 Oct 2008: ColumbusDay
Fri, 24 Oct 2008: UnitedNationsDay
Fri, 31 Oct 2008: Halloween
Tue, 04 Nov 2008: ElectionDay
Tue, 11 Nov 2008: VeteransDay
Thu, 27 Nov 2008: Thanksgiving
Fri, 28 Nov 2008: DayAfterThanksgiving
Wed, 24 Dec 2008: ChristmasEve
Thu, 25 Dec 2008: Christmas
Wed, 31 Dec 2008: NewYearsEve
| list |
list := SortedCollection sortBlock: [:a :b | a value < b value].
SemanticDatePolicy unitedStates
nominalAnnualEventOccurenceDatesInYear: 2008 do:
[:semanticKey :date | list add: semanticKey->date].
Transcript cr.
list do:
[:assoc |
Transcript
cr; show: (assoc value printStringUsing: #rfc2822);
show: ':'; tab; show: assoc key]
Timepoint now showInCommonWorldTimezones
Tue, 01 Jan 2008 13:55:54 +1300 (NZDT: Pacific/Auckland | New Zealand Time)
Tue, 01 Jan 2008 11:55:54 +1100 (EST: Australia/Sydney | AUS Eastern Time)
Tue, 01 Jan 2008 09:55:54 +0900 (JST: Asia/Tokyo | Tokyo Time)
Tue, 01 Jan 2008 09:55:54 +0900 (WST: Australia/Perth | W. Australia Time)
Tue, 01 Jan 2008 08:55:54 +0800 (HKT: Asia/Hong_Kong)
Tue, 01 Jan 2008 06:25:54 +0530 (IST: Asia/Calcutta | India Time)
Tue, 01 Jan 2008 03:55:54 +0300 (MSK: Europe/Moscow | Russian Time)
Tue, 01 Jan 2008 02:55:54 +0200 (IST: Asia/Jerusalem | Israel Time)
Tue, 01 Jan 2008 01:55:54 +0100 (CET: Europe/Amsterdam)
Tue, 01 Jan 2008 00:55:54 +0000 (GMT: Europe/London | London Time)
Tue, 01 Jan 2008 00:55:54 +0000 (UT: Universal Time)
Mon, 31 Dec 2007 22:55:54 -0200 (BRST: America/Sao_Paulo | E. South America Time)
Mon, 31 Dec 2007 21:55:54 -0300 (ART: America/Argentina/Buenos_Aires)
Mon, 31 Dec 2007 19:55:54 -0500 (EST: America/New_York | Eastern Time)
Mon, 31 Dec 2007 18:55:54 -0600 (CST: America/Chicago | Central Time)
Mon, 31 Dec 2007 17:55:54 -0700 (MST: America/Denver | Mountain Time)
Mon, 31 Dec 2007 16:55:54 -0800 (PST: America/Los_Angeles | Pacific Time)
Mon, 31 Dec 2007 14:55:54 -1000 (HST: Pacific/Honolulu | Hawaiian Time)
Timepoint now showInAllCalendars
Local time is America/Los_Angeles ("Pacific Standard Time")—8 hours west of Universal Time
2007-12-25 AD @ 9:00:15 am -0800 [Gregorian]
0164-15-14 BE @ 9:00:15 am -0800 [Bahai]
1724-04-15 AM @ 9:00:15 am -0800 [Coptic]
2000-04-15 ZH @ 9:00:15 am -0800 [Ethiopic]
5768-10-16 AM @ 9:00:15 am -0800 [Hebrew]
1929-10-04 AS @ 9:00:15 am -0800 [Indian Civil]
1428-12-15 AH @ 9:00:15 am -0800 [Islamic (Fatimid)]
2007-12-12 AD @ 9:00:15 am -0800 [Julian]
2760-12-12 AUC @ 9:00:15 am -0800 [Julian (Imperial)]
1386-10-04 AP @ 9:00:15 am -0800 [Persian]
6244-01-04 SY @ 9:00:15 am -0800 [Solarian]
2007-359 @ 9:00:15 am -0800 [Gregorian-ordinal date]
2007-W52-2 @ 9:00:15 am -0800 [ISO]
J.D. 2454459 @ 9:00:15 am -0800 [Julian Day]
39074:17:00:15.077734 days:hh:mm:ss.s.. since 1901-01-01T00:00:00Z (ST80 epoch)
1198602015 seconds since 1970-01-01T00:00:00Z (Unix epoch)
128430756150777340 100-nanosecond ticks since 1601-01-01T00:00:00Z (MS WIndows epoch)
Christmas
Version 2007j of the Chronos Time Zone Repository has been published. It is based on version 2007j of the Olson Time Zone Database.
Downloads:
Both Travis Griggs and David Buck have recently published their contributions to the "Smalltalk in One Page" project. So I thought I'd provide my condensed specification of Smalltalk syntax (which is excerpted from my Smalltalk primer/tutorial, Smalltalk: Getting The Message):
Below is presented the full and complete formal specification of the syntax (grammar) of ANSI-Standard Smalltalk, using a metalanguage known as Extended Backus-Naur Formalism (EBNF). The specific flavor of EBNF syntax used is as specified by the ISO International Standard for EBNF.
The EBNF grammar of Smalltalk is presented as a list of numbered production rules. Note that there are only 67 production rules, that five of them simply define aliases (alternative names) solely for conceptual clarity, and that over half the production rules concern themselves with literal values, comments, identifiers and other low-level lexical constructs.
[Updated URL; referenced document was relocated]
I have written a Smalltalk primer/tutorial. It takes a different approach than other programming language primers or tutorials I have seen on the web.
Firstly, it does not assume that the reader knows the syntax of any particular programming language, although it does assume that the reader either knows how to program, or at least that he is comfortable with the relevant mathematics and foundational concepts.
Secondly, it first explains the computational model of Smalltalk, before presenting any Smalltalk syntax.
Thirdly, it takes a bottom-up approach to the presentation of Smalltalk syntax, starting with lexical tokens and ending with method declarations.
Finally, it stresses the importance of messages above all else, and shows how and why those who have attempted to copy Smalltalk in other programming languages failed to "get the message."
Constructive criticism, suggested rewordings to improve clarity, and requests that additional information be included or that additional topics be covered, are encouraged. Such requests should be sent to the author, Alan L. Lovejoy, at the following e-mail address: smalltalk-tutorial (at) alan-lovejoy (dot) net.
Enjoy!
 | Smalltalk: Getting The Message The Essentials of Message-Oriented Programming with Smalltalk |
Object-orientation: In Smalltalk, all values are objects—even integers and other numbers, characters, strings, classes and blocks of code. Smalltalk is one of the first object-oriented programming languages. Its design was influenced by Lisp, Logo, Sketchpad, Flex and Simula. Smalltalk was developed as a research project at Xerox PARC in the 1970s by a team whose members included Dr. Alan Kay, Dan Ingalls, Adele Goldberg, Ted Kaehler, Scott Wallace and others.
Warning: Terms such as "object," "class," "type," "method" and hence "object-oriented programming" itself, as used in the context of Smalltalk, do not have the same meanings as they do when used in the context of other programming languages. The term object-oriented programming ("OOP") was coined by Dr. Alan Kay, the inventor of Smalltalk. He intended the term to describe the essential nature of Smalltalk. Unlike Smalltalk, most of the programming languages that market themselves as "object oriented" do not satisfy Dr. Kay's definition of object oriented programming:
"OOP to me means only messaging, local retention and protection and hiding of state-process, and extreme late-binding of all things. It can be done in Smalltalk and in LISP. There are possibly other systems in which this is possible, but I'm not aware of them."
Version 2007g of the Chronos Time Zone Repository has been published. It is based on version 2007g of the Olson Time Zone Database.
Downloads:
SOUTHERN Cross University (New South Wales, Australia) has a rather unique problem: They're establishing a new campus at the Gold Coast Airport Development Park, which will straddle the Queensland-NSW border on Crown land abutting the southern side of the Gold Coast Airport. New South Wales observes DST. Queensland does not.
Civil time will shift back and forth by an hour in NSW, but not in Queensland. So how will classes be scheduled? What about work schedules? Vice Chancellor Paul Clark said "We will probably be the guinea pigs in many ways because there's nowhere else in Australia with feet in two different states."
Now consider this question: How well would your software handle a case like this? Would your date/time library even be up to the task?
The Ruby on Rails community has provided us with a canonical "how to" for marketing a dynamic programming language: Ruby on Rails vs Java.
Where's the Smalltalk version?
VisualWorks 7.5 was released (finally!) a few days ago. For the first time, the Chronos Date/Time Library is included as a contributed component.
However, I would like to make everyone aware of the following points:
One more reason to use Chronos: Boy jailed over clock change mix-up.
You should also update your time zone rules on a regular basis.
Version 2007e of the Chronos Time Zone Repository has been published. It is based on version 2007e of the Olson Time Zone Database.
Downloads:
Version 2007d of the Chronos Time Zone Repository has been published. It is based on version 2007d of the Olson Time Zone Database.
Downloads:
Due to the changes at Planet Smalltalk, which have invalidated all URLs to old articles, and due to the fact that Google searches are still preferentially returning results to now-invalid URLs at Planet Smalltalk, I am republishing the following information:
