Apl – a programming language

Apl – a programming language

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  APL – AProgramming Language By Bryan Wilson
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  //TODO - Header • Short History • Brief APL Rundown • APL Details and Tools • Syntax – Data, Structures, Classes – Functions, Operands – System Variables, Functions • Expanding APL
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  30 Second History •This language is crazy • History sheds light on why
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  Enter Kenneth E.Iverson Profession: Mathematics “5 is greater than 1. Look”
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  His Notation Relic foundin ancient Mayan ruins.
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  A Pointless Language • Entirely dynamic, highly abstract • Largely interpreted (line by line execution) • “Keywords” are symbols • Tacit programming • Short programs, probably about 1 line • Write-only language
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  How the magichappens • Right to left evaluation, except for parens 5 + 5 10 5 x 5 25 5 × 5 + 5 50 (5 × 5) + 5 30
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  Time to getcrazy • Types of data are largely done for you 1 2 3 + 5 6 7 8 ¼9 1 2 3 4 5 6 7 8 9 2 4 ½¼9 1 2 3 4 5 6 7 8 9 1 2 3 4 5
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  Stop. Demotime.
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  Boring APL stuff •Specifications – ISO (International Standards Organization – APL2, by IBM • Interpreted – Thus, Interpreters • APL+ • APLX • Dyalog APL • VisualAPL
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  Interpreters • Use workspaces,and have unique specs – Workspace – System Variables – System Functions • Modes – Calculator mode – Definition mode
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  Simple Data • Anumber – 24595 – Can be decimal or negative • A character – ‘s’ – Wrapped in single quotes – ‘Use two ‘’ to escape the ‘’ ‘
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  Data Structures • Mayhave data, has dimensions • Data does not have dimensions • Struct – 1 item, no dimensions • Vector- 1d list of items • Matrix -2D..nD list of items • Item can be character, number or structure • Data structures can have mixed data, or nested
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  Data and structuresyntax • To store a variable [name] „ [variable] • Names can start with a letter and NOTHING else • Names can have numbers and some symbols • Don’t duplicate names
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  Functions • Types – 0 arguments (niladic) – 1 argument (monadic) • Everything to the right – 2 arguments (dyadic) • Everything to the right • First item to the left • Can return data/data structure • Bucket brigade • Can be named like data • One symbol, 1-2 functions, depending on arguments
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  Operations • Modify thefunction of…functions. – How functions are applied to data • In addition to 0-2 arguments, can take 1-2 operands • Functions can be operands • Can also be named like functions
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  Classes • Logical groupingof data and functions „ŒNEW CLASSNAME [classname].[function/property] • Can have constructors. • Some interpreters let you use external classes – .NET
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  Alienspeak • Arithmetic +, -, ×, ÷, ⌈, ⌊, | • Algebraic ⍳ , ? , * , ⍟, ○, ! , ⌹ • Comparative <, ≤, =, ≥, >, ≠, ≡, ∊, ⍳, ⍷ • Logical ~, ∨, ^, ⍱, ⍲ • Manipulative ⍴, ≡, , , ∊, ~, ⌽, ⍉, ↑, ↓, ⊂, ⊃
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  Continued Mathyspeak • Sorting ⍋, ⍒, ⊤, ⊥ • Miscellaneous ⎕, ⍞, ⋄, ⍕, ⍝, ⍎, ⌷, ⌻,¯ • Operators /, , ., ∘. , ¨, [ ]
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  Defining your ownfunctions • It can be done! Watch!
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  System Variables andFunctions • Variables – Easy to pick out, they start with Œ – Change depending on interpreter • Functions – Start with a ) – Also change depending on interpreter
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  Can’t cover everything! •Can you have threads? – Yes. Some interpreters. • Can you have labels? – In function and operation definitions. – This includes if/else and try/catch blocks • Where can I learn more? – Classes quoted at ~$2000 per day per person
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  The future isJ • APL transformed to be easier to read quicksort=: (($:@(<#[), (=#[), $:@(>#[)) ({~ ?@#)) ^: (1<#)
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  Summary • Simply put: – Dynamic – Abstract – Powerful – Awesome
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  Questions for YOU 1.⍳9 Returns what? 1 2 3 4 5 6 7 8 9 2. What does an operator in APL do? Changes how a function is applied to data 3. To create a 3 dimensional array: (1 2 3) ⍴ (5 4)
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  Questions for me? Thereare three things a man must do before his life is done write two lines in APL, and make the damn thing run