[Haskell-beginners] eval command?

Brent Yorgey byorgey at seas.upenn.edu
Mon Oct 27 19:45:26 EDT 2008

On Mon, Oct 27, 2008 at 07:00:00PM -0400, Brandon S. Allbery KF8NH wrote:
> On 2008 Oct 27, at 17:33, Alex Shearn wrote:
>> Hey all - I've been trying to write an IRC bot following the guide on the 
>> wiki, and we (those of us on the channel) were trying to get it to 
>> evaluate commands.
>> So far, we have this for "eval" stuff, but is there anyway to specify a 
>> "parse in haskell" sort of thing?
> No, although you could fake it with the GHC-API (which basically means your 
> bot has all of GHC built into it).
> In any case, that's not really a good idea; consider what damage could be 
> done by arbitrary code.  A better idea is to link the code into a small 
> program with a very restricted environment and run that with a timeout.  
> See http://code.haskell.org/lambdabot/Plugin/Eval.hs.

Brandon is right that this is difficult and tricky -- but fortunately,
someone else has already done the hard work for you!  Take a look at
the mueval package [1], which should allow you to do what you want.


[1] http://hackage.haskell.org/cgi-bin/hackage-scripts/package/mueval

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