Difference between revisions of "Research area"
(Rearch area = the golden mine of mine) |
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a type , without recompiling existing code, and while retaining static type safety." | a type , without recompiling existing code, and while retaining static type safety." | ||
| − | + | [[Image:The_Expression_problem_Solved_untill_2008.png]] | |
| + | |||
| + | |||
| + | Ten years later a simple and clear solution (2008) was given by Dan Popa [[User:Ha$kell]] in a speech scheduled for [[AngloHaskell/2008]] http://www.haskell.org/haskellwiki/AngloHaskell/2008 | ||
You may download the presentation from http://www.haskell.org/sitewiki/images/1/1d/Prezentare-Anglo-Haskell-2008-draft2-more-slides.pdf | You may download the presentation from http://www.haskell.org/sitewiki/images/1/1d/Prezentare-Anglo-Haskell-2008-draft2-more-slides.pdf | ||
Why this solution is so interesting and so new: | Why this solution is so interesting and so new: | ||
| − | + | * it did not use a fixpoint operator !! | |
| − | + | * it did not use a Maybe (high level embeded) type !! | |
| − | + | * it did not propose a Haskell extension !! | |
| − | + | * it did not use '''data''' declaration anymore !! | |
| + | * as a consequence it did not use Data Constructors anymore !! | ||
| + | * it is introducing ''pseudoconstructors over monadic values'' because the chain of unevaluated (yet) functions is actually forming a datastructure . do not forget that Haskell is a lazy evaluation language !! | ||
Why this solution is valuable: | Why this solution is valuable: | ||
| − | + | * because we have already built modular languages like [[Rodin]] using it. | |
| − | + | * because it works with just a bit overloading of the system : See final pages of http://www.haskell.org/sitewiki/images/1/1d/Prezentare-Anglo-Haskell-2008-draft2-more-slides.pdf | |
| − | + | * because it is modular | |
| − | + | * because language construction tools are valuable software (1000$ a Licence for a good language generator.) | |
| − | + | * because it fits in the previous kind of systems with truee small modifications (just replace a single letter of a data constructor to transform it in a pseudoconstructor ...) | |
| − | + | * because my Ph.D Superviser is wishing to sell custom languages with a price of aprox 10 000$ / language - or at least he declared this some times ago. | |
References: see the .pdf of the latest papers from [[User:Ha$kell]]'s homepage. | References: see the .pdf of the latest papers from [[User:Ha$kell]]'s homepage. | ||
| Line 34: | Line 39: | ||
==. References == | ==. References == | ||
| − | + | Dan Popa, "Modular evaluation and interpreters using monads and type classes in Haskell" , Studii si Cercetari Ştiinţifice, Seria Matematica, Univ. Bacău, (18) 2008. An Open Office (.sxw) file ''including example code'' is available here: | |
| − | Dan Popa, "Modular evaluation and interpreters using monads and type classes in Haskell" , Studii si Cercetari Ştiinţifice, Seria Matematica, Univ. Bacău, (18) 2008. An Open Office (.sxw) file is available here: | ||
[http://www.haskell.org/sitewiki/images/1/15/Paper-v5.sxw Download .sxw ] After loading the .sxw in the Open Office, press the PDF button from the toolbar to produce your own .pdf file. Or | [http://www.haskell.org/sitewiki/images/1/15/Paper-v5.sxw Download .sxw ] After loading the .sxw in the Open Office, press the PDF button from the toolbar to produce your own .pdf file. Or | ||
[http://www.haskell.org/sitewiki/images/7/7d/POPA_D.pdf Official PDF of the paper for <DOWNLOAD> ], having the following title: | [http://www.haskell.org/sitewiki/images/7/7d/POPA_D.pdf Official PDF of the paper for <DOWNLOAD> ], having the following title: | ||
Revision as of 08:10, 3 June 2009
Contents
. The Expression Problem
In 1998 P.Wadler had defined "The Expresion Problem" (accordingly to Wouter Swierstra - Data types a la carte ).
"The goal is to define a data type by case, where one can add new cases to the data type and new functions over the dat a type , without recompiling existing code, and while retaining static type safety."
Ten years later a simple and clear solution (2008) was given by Dan Popa User:Ha$kell in a speech scheduled for AngloHaskell/2008 http://www.haskell.org/haskellwiki/AngloHaskell/2008
You may download the presentation from http://www.haskell.org/sitewiki/images/1/1d/Prezentare-Anglo-Haskell-2008-draft2-more-slides.pdf
Why this solution is so interesting and so new:
- it did not use a fixpoint operator !!
- it did not use a Maybe (high level embeded) type !!
- it did not propose a Haskell extension !!
- it did not use data declaration anymore !!
- as a consequence it did not use Data Constructors anymore !!
- it is introducing pseudoconstructors over monadic values because the chain of unevaluated (yet) functions is actually forming a datastructure . do not forget that Haskell is a lazy evaluation language !!
Why this solution is valuable:
- because we have already built modular languages like Rodin using it.
- because it works with just a bit overloading of the system : See final pages of http://www.haskell.org/sitewiki/images/1/1d/Prezentare-Anglo-Haskell-2008-draft2-more-slides.pdf
- because it is modular
- because language construction tools are valuable software (1000$ a Licence for a good language generator.)
- because it fits in the previous kind of systems with truee small modifications (just replace a single letter of a data constructor to transform it in a pseudoconstructor ...)
- because my Ph.D Superviser is wishing to sell custom languages with a price of aprox 10 000$ / language - or at least he declared this some times ago.
References: see the .pdf of the latest papers from User:Ha$kell's homepage. Ill be back. Download and read the latest papers of Dan Popa from User:Ha$kell's homepage.
. Classic complex solutions
... will be added
. Monadic Interpretation
... will be added
. References
Dan Popa, "Modular evaluation and interpreters using monads and type classes in Haskell" , Studii si Cercetari Ştiinţifice, Seria Matematica, Univ. Bacău, (18) 2008. An Open Office (.sxw) file including example code is available here: Download .sxw After loading the .sxw in the Open Office, press the PDF button from the toolbar to produce your own .pdf file. Or Official PDF of the paper for <DOWNLOAD> , having the following title:
Direct modular evaluation of expressions using the monads and type classes in Haskell by DAN V. POPA UNIVERSITATEA DIN BACĂU STUDII ŞI CERCETĂRI ŞTIINŢIFICE Seria: MATEMATICĂ Nr. 18 (2008), pag. 233 – 248
The paper is introducing Pseudoconstructors over monadic values as a way of building modular trees without data or Haskell extensions. http://www.haskell.org/sitewiki/images/7/7d/POPA_D.pdf. Modular adaptable interpreters for extensible languages - like Rodin - become now easy to build, without the need of any Haskell extensions.
more
... will be added
. History of the domain
... will be added