[Haskell] Re: RE: Extensible records: Static duck typing

2008-02-18 Thread Ben Franksen
[I replied on @cafe but didn't get any response. Trying again here.]

Barney Hilken wrote:
>> What about just implementing the cheapest solution that still gets
>> us most
>> of the way?
> 
>> (3) If it is as cheap (to implement) as advertised then there is no
>> great
>> risk involved. If it turns out the missing features are a great
>> show-stopper for some people (which I don't believe) then let them
>> present
>> their case afterwards, with good examples at hand. We can still
>> decide to
>> aim for a higher goal in the long term.
> 
>> If in doubt, chose the solution that is easier to implement.
> 
> Since this paper, there have been several proposals which can be 90%
> implemented as libraries, using either functional dependencies or
> associated types. These all have much more expressive type systems
> than the SPJ paper, yet need very little compiler support. The
> question is, which one (if any) should get this small but necessary
> support?

Could you be more specific? Which proposals exactly do you mean and where
can I read more about them?

(I know about HList/OOHaskell which is ingenious, of course, but not even
the authors propose that a new Record System for Haskell should be based on
their library, compiler support or no.)

Cheers
Ben

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Re: [Haskell] Re: RE: Extensible records: Static duck typing

2008-02-18 Thread Barney Hilken

Begin forwarded message:


From: Ben Franksen <[EMAIL PROTECTED]>
Date: 18 February 2008 21:32:29 GMT
To: haskell@haskell.org
Could you be more specific? Which proposals exactly do you mean and  
where

can I read more about them?


Hlist is one of the ones | was thinking of. Two more are "poor man's  
records" a.k.a. Data.Record.hs, whose author certainly believes it  
should be the basis for the new system, and my own system,  
downloadable from http://homepage.ntlworld.com/b.hilken/files/Records.hs


There is a discussion of the various possibilities on the wiki
http://hackage.haskell.org/trac/ghc/wiki/ExtensibleRecords
which you are encouraged to contribute to!

Sorry about the lack of response on cafe, but I only read that when  
people say they are moving their discussion there.


Barney.

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