a universal printer for Haskell?

Hal Daume III hdaume@ISI.EDU
Tue, 19 Feb 2002 07:22:29 -0800 (PST)


Doesn't Hugs basically do just this when you don't have +u set?  Why not
simply mimick their approach?  I mean, sure, it's not written in haskell,
but does that really matter for the printing for debugging issue?

 - Hal

Hal Daume III

 "Computer science is no more about computers    | hdaume@isi.edu
  than astronomy is about telescopes." -Dijkstra | www.isi.edu/~hdaume

On Tue, 19 Feb 2002, Bernard James POPE wrote:

> Hi Christoph and all,
> > > Bernie: talking about universal printer...
> > yes, I'm such a Haskell programmer that would like such a mechanism but
> > it only makes sense for me if you also have the inverse function.
> For the simple scheme I presented the inverse is easy enough.
> > In this case, you could save the state of your computation on disk and
> > recover it later, send run-time functions to a remote machine 
> > and execute them on that machine with full control by the programmer.
> > This marshalling/unmarshalling mechanism is provided partially by
> > some Haskell tools. 
> Handling functions is always going to be hard. Actually, a related issue
> in Haskell is what do you do with partially evaluated structures? 
> Certainly in some circumstances you don't want to force the value just so
> that you can write it out. If you compiled to byte code, life would be a lot
> easier, however everything will get a lot messier if you want to mix
> machine code and byte code. urgh...
> I carefully avoided functions, because they require a lot more effort.
> > Probably the reason that this mechanism doen't exist in Haskell yet is that
> > it is difficult to implement. 
> It is especially difficult if you want to make persistent data across
> different implementations of the language. It would be nice if you
> could write out some data to file from GHC and then read it in using NHC :)
> There are obviously various degress of "persistence".
> I think Clean has a prototype persistence mechanism, I saw a short demo
> late last year. I'm not sure how they represent functional values. 
> I think you can only read the data from within the same program that wrote
> the data.
> Cheers,
> Bernie.
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