Re: [luca_ciciriello@hotmail.com: Re: [Haskell-beginners] reflection]

Brent, thanks for your precious help. Luca On Jan 5, 2010, at 6:41 PM, Brent Yorgey wrote:

Well, there are a few things I could suggest for you to look at:

* the hint package [1] for runtime Haskell interpretation * look at xmonad [2] for an example of a program which recompiles and reloads itself on the fly * the haskell-src-exts library [3] for a full-featured Haskell parser/pretty printer

There is no way to actually inspect and modify the structure of a running Haskell program in memory; it is simply not stored in a format which would let you do this (it is highly optimized and compiled). However, using the above tools I imagine you should be able to accomplish what you want.

-Brent

[1] http://hackage.haskell.org/package/hint [2] http://xmonad.org/ [3] http://hackage.haskell.org/package/haskell-src-exts

----- Forwarded message from Luca Ciciriello -----

From: Luca Ciciriello Date: Tue, 5 Jan 2010 18:20:13 +0100 To: Brent Yorgey Subject: Re: [Haskell-beginners] reflection

My need is to have a program that at run-time should be able to read itself and eventually modify itself. I've used this reflection in Common LISP. I don't know if this is possible in Haskell using GHC or GHCi (perhaps there are more chances inside the eval-loop of GHCi).

Thanks anyway for the answer.

Luca.

On Jan 5, 2010, at 5:58 PM, Brent Yorgey wrote:

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On Tue, Jan 05, 2010 at 09:43:21AM +0100, Luca Ciciriello wrote:

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Hi. Someone has performed or know how to use reflection in Haskell? I've found something on google, but that stuff seems to me very confusing.

It depends what you mean by "reflection". Can you give an example of the sorts of things you'd like to do? Generally speaking, Haskell doesn't support "reflection" in the same way as many other languages do, but there are usually idiomatic ways to accomplish the same things you would use reflection for.

-Brent _______________________________________________ Beginners mailing list Beginners@haskell.org http://www.haskell.org/mailman/listinfo/beginners

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