CS 199 Computers UnpluggedCourse Notes1

Week 4: Natural and Programming LanguagesLecture 2: Programming Languages

Anton Setzerhttp://www.cs.swan.ac.uk/∼csetzer/index.html

http://www.cs.swan.ac.uk/∼csetzer/lectures/computersUnplugged/10/index.html

November 5, 2010

1Substantially based on Stephen Anderson: How many languages are there in theworld. Available from http://www.lsadc.org/info/pdf files/howmany.pdf

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How Many Programming Languages are there in thisWorld?

I Number of languages linked from at HOPL:I Same problems as for natural languages:

I Families of languages.I Dialects.I Different versions.I Different compilers for the same language execute differently.

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What is a Programming Language?

I The Free Dictionary http://www.thefreedictionary.com:I An artificial language used to write instructions that can be translated

into machine language and then executed by a computer.

I Wikipedia http://en.wikipedia.org/wiki/Programming languageI A programming language is an artificial language designed to express

computations that can be performed by a machine, particularly acomputer

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What is a Programming Language?

I Britannica Onlinehttp://www.britannica.com/EBchecked/topic/130670/computer-programming-language

I Computer programming language, any of various languages forexpressing a set of detailed instructions for a digital computer.

I Webopediahttp://www.webopedia.com/TERM/P/programming language.html

I A vocabulary and set of grammatical rules for instructing a computerto perform specific tasks

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What is a Programming Language?

I My definition:I A

::::::::::::::programming

::::::::::language is a set of descriptions such that each

description can be used to instruct a computer or other mechanicaldevice to perform a specific task.

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What is a Language?

I An::::::::::alphabet is a finite set.

I A:::::::formal

:::::::::::language is a set of strings over a given alphabet.

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What is a Programming Language?

I Is mp3 a programming language?I Analogue computer languages.

I Not formal languages.

I Is English a programming language?

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Adjustment Mechanism of a Mechanical Watch – AnAnalogue Programming Language

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Vynil Record – Analogue Programming Language

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Antikythera Mechanism

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Antikythera Mechanism

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Antikythera Mechanism (around 150 - 100 BCE)

I From http://en.wikipedia.org/wiki/Computer programming:I The Antikythera mechanism from ancient Greece was a calculator

utilizing gears of various sizes and configuration to determine itsoperation, which tracked the metonic cycle still used in lunar-to-solarcalendars, and which is consistent for calculating the dates of theOlympiads.

I From Mark Wonnacott: Analogue Computers: The First DeclarativeProgramming.http://ragzouken.com/compsci/languages.pdf

I The first machine computable delcarative program is within the earliestmechanical computer, the Antikythera mechanism (c. 70 BC).Changing the date with the mechanism’s hand-crank turned a complexarrangement of gears to compute astronomical positions. Differentgearing rations between connected gears dictate the relationshipsbetween them and ultimately between the date and calculatedastronomical positions. These relationships are invariantly satisfied bythe turning of the gears, making the gears a form of declarativeprogram.

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Al-Jazari Musical Robots – A Digital ProgrammingLanguage

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History of Programming Languages

I Wikipedia, http://en.wikipedia.org/wiki/Al-JazariI l-Jazari created a musical automaton, which was a boat with four

automatic musicians that floated on a lake to entertain guests at royaldrinking parties. Professor Noel Sharkey has argued that it is quitelikely that it was an early programmable automata and has produced apossible reconstruction of the mechanism; it has a programmable drummachine with pegs (cams) that bump into little levers that operated thepercussion. The drummer could be made to play different rhythms anddifferent drum patterns if the pegs were moved around. According toCharles B. Fowler, the automata were a ”robot band” which performed”more than fifty facial and body actions during each musical selection.”

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Jacquard Loom (Invented 1801)

Jacquard Loom, invented by Joseqph Marie Jacquard 1801

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Babbage’s Analytical Engine (1834)

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Babbage’s Analytical Engine – First Turing CompleteLanguage

I It’s Turing complete.I More in CS-236 Lanugage and Computation.

I Any computable function can be computed in principle usingBabbage’s Analytical Engine.

I The language for Babbage’s Analytical Engine is probably the firstTuring-Complete Programming Language.

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Ada Lovelace - The first Computer Programmer

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Hello World Program

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99 Bottles of Beer

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Popular Languages

I Java

I C

I C++

I Pascal

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Scripting Languages

I Perl

I Python

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Easy to Use Languages

I BASIC

I Visual Basic

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Functional Programming Languages

I Haskell

I SML

I Coq (dependently typed)

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Logic Programming

I Prolog

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Markup Languages/Spreadsheets

I HTML

I Excel

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Misc

I Database LanguagesI SQL

I Graphical LanguagesI LabVIEW

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Historically Famous Languages

I Babbage’s Analytical Language

I ENIAC

I FORTRAN

I LISP

I Cobol

I Simula

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Assembler

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Theoretical Languages

I Turing Machine

I CSP

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Extreme Languages

I SheerPower.I Aimed at having the fastest compilation.I What does this mean?

I Brainfuck.I Aimed at having thesmallest compiler.I What does this mean?

I MalbolgeI Aimed at having the most incomprehensible language.

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Esoteric Languages

I Cow.

I LOLCODE.

I Piet.

I Whitespace.

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