Cleenewerck'Thomascs'kuleuven'ac'be

1
Capturing and using emergent knowledgeby keyword
based programming

• Cleenewerck.Thomas_at_cs.kuleuven.ac.be
• Katholieke Universiteit Leuven
• June-??, 2002

2
Talk

• Terminology
• Building DSLs/Technology
• Experience (problems)
• Other approaches
• Macros, Java Syntactic Extender
• Jakarta Tool Suite
• Intentional Programming
• Future work

3
Terminology

• ...elements which do not start out with a
  keyword, like expressions, orstatements...Can
  be ANY linguistic component
• 26653
• TYPE VAR
• for( ... ... ....) ...

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Terminology (2)

• Keyword based programming
• atomistic programmming / language design
• contemporary
• ALC programming (Atomic Linguistic Component
  programming)
• Tool oriented programming
• Human oriented programmming
• Emergent

5
DSL

• Extending languages using compiler plug-ins
  implementing single keywords
• Plug play components for a language
• Modularized
• Re-usable
• Same DSL
• Cross DSLs
• Stand alone
• Realize their effects
• Active
• Composable language
• Language specificiationComposing configuring
  L-components
• Vertical Linguistic components
• Lexer parser (backtracking left recursion
  descent)
• Generator
• Interkeyword communication

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Keyword

• keyword time
• AST
• public class AST
• keyword body
• RecognitionPattern
• ( time, , keyword body, )
• generator
• public JavaStatements generate()
• JavaStatements js generate body
•  
• gtgt long aXX System.currentTMillis()
• gtgt js
• gtgt System.out.println(action has taken
  (System.currentTimeMillis() aXX))

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Language specification

• Reusability
• Parametrisation
• Relations with other keywords
• Fixed
• Repository
• Choice between what is fixed and what is variable
• Syntax of the parent public TYPE(id TYPE, ...)
  STATEMENTS
• Generator of the child TYPE returns a
  String STATEMENTS returns a
  java.ast.Statement
• ltkeyword type"keywords.java.MethodDeclaration"
  id"methoddecl"gt
• ltparam name "type"gt
• ltkeyword refid"packageof"/gt
• ltkeyword refid"astclass"/gt
• ltkeyword refid"class"/gt
• lt/paramgt
• ltparam name "statements"gt
• ....
• lt/paramgt
• lt/keywordgt
• Auto-transformations keywords without or
  optional syntax

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Generator

• Does not replace AST nodes! (parametrisation)
• ? keyword ?? a generator
• Targetting (Anything)
• Active
• Passive (code generators)
• Walking the target AST
• Local Non-local Effects (observing target AST
  AST member with empty binding)
• After parsing
• Root keyword generator is created, and initiated
• Keyword K with parameters (P1, ... , Pn)
• Generators are created
• A method is called to initiate generation
• Keyword child restrictions
• Return type
• Parameters (property bags)
• MethodName

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Related workJakarta Tool Suite

• Language ContextInteraction between linguistic
  componentsis embedded in the keyword itself
• Communication via source AST
• Via target tree
• Syntax dependentSyntax dependent retrieval of
  information in generatorarg0 en arg1
• Non-direct effects
• Encapsulation of the syntax of a linguistic
  component
• Fielddeclaration public type() var()
• Whole language extensions

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Related workMacros, Java Syntactic Extender

• Language
• Context in which keywors can be used
• Context in which their effect is semantically
  valid
• Scheduling of language components
• Syntax
• freedom vs limited and simple ASTs
• shared syntax/information sharing
• New languages/Legacy languages
• Reuse of linguistic components
• Acces to other context information

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Related workExplicit Programming

• Syntax Tagging of language constructs
• Semantics java methods using reflection
• Sheduling
• requiresltnamegt gets executed after
  satisfiedltnamegt
• Closely related to macros

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Experience

• Languages
• Installer 57 keywords
• EJava 45 keywords
• Java 36 keywords
• Implicit model
• How code is emmited
• Target model (tree, outputstream, ...)
• constraints
• Interrelations/Parametrisations
• Encapsulation of interoperabilities
• Behaviour, initialisation, etc.
• Non direct transformations
• Special support
• Relocating
• Dummy ReturnValues
• Manual composition

13
Future work

• Language specifications keywords
• Composability
• Management
• Generating quotation language extentions int
  a out of language specification
• Interpreteded Templates
• Compiled Templates
• Keyword dependencies

14
Comments

• "Making choices between languages (AspectJ,
  MacroJ, C, SmallTalk, Self, ...) supporting
  different features is no longer." - This sentence
  makes little sense. The differences between these
  languages are more than just syntactic ones! You
  can only have translation from a DSL to any of
  them.
• but argues for thelanguage as a domain modelling
  issue as well.