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Re: Initial Draft Finding on Principle of Least Power

From: Harry Halpin <hhalpin@ibiblio.org>
Date: Thu, 22 Dec 2005 13:37:20 -1000
Message-ID: <43AB38B0.1080900@ibiblio.org>
To: noah_mendelsohn@us.ibm.com
Cc: Graham Klyne <GK@ninebynine.org>, www-tag@w3.org

This is an immensely minor point, but if interested:

I definitely think mentioning functional programming is a good idea,
with Haskell being a fine example (there's lots of interesting
functional programming work going on in relation to the Web [1]).

I just read that paragraph:

"Computer languages range from the plainly descriptive (such as Dublin
Core metadata, or the content of most databases, or HTML), through
logical languages with limited propositional logic (such as access
control lists, or /conneg/ content negotiation), through declarative
languages that verge on the Turing Complete (PDF), through those which
are in fact Turing Complete though one is led not to use them that way
(XSLT, SQL), through those that are functional and Turing complete
(Haskell), to those which are unashamedly procedural (Java, Javascript, C).

and assumed that the paragraph was ranking the languages by "power" as
defined by Turing-completeness and by something a bit more subtle
(analyseability/complexity/ease-of-use/?), which seems to be the
sensible thing to do with an example.  The concept of "power" is hard to
pin down, one that cross-cuts in non-trivial and subjective ways, but
clearly a principle that is central to why the Web works so well.

My initial reaction was:
 "through *powerful* Turing complete programming languages that are
functional (Haskell) *and* those that are unashamedly procedural (Java,
Javascript, C)."

Still unsatisfying :) But now I can see how Graham and Noah got the
first "pro-functional" reading out of the statement. Perhaps in case
where the subject matter is intuitive and sometimes subjective having
statements be open to interpretation is not a bad thing!
  
 cheers,
          harry

[1]http://www.ibiblio.org/hhalpin/homepage/notes/links.html






noah_mendelsohn@us.ibm.com wrote:



>Graham Klyne writes:
>
>  
>
>>I'm biased in this respect, but I rather liked the reference to
>>Haskell.  In particular, I thought the text was clear enough 
>>(to me) that Haskell was no less powerful, but also carried the
>>suggestion that somehow pure functional expressions are more 
>>amenable to the proffered advantages of less power.
>>    
>>
>
>Thanks.  That's certainly what I intended when I added it.  I think that 
>functional languages are a very interesting point on the 
>power/complexity/analyseability scale, as they have all the expressive 
>power of Turing completeness, but can be reasoned about in ways that are 
>difficult with procedural languages.
>
>So, I was a bit disappointed when the first response (from Harry Halpin) 
>worried that the text could be taken as criticising rather than supporting 
>the best aspects of functional languages.  I don't think this is worth a 
>flame war, but I'll be curious to see how other readers took it.  Thanks!
>
>Noah
>
>--------------------------------------
>Noah Mendelsohn 
>IBM Corporation
>One Rogers Street
>Cambridge, MA 02142
>1-617-693-4036
>--------------------------------------
>
>
>
>
>
>  
>
Received on Thursday, 22 December 2005 23:37:24 UTC

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