[plt-scheme] [redex] what computation is happening?

From: Matthias Felleisen (matthias at ccs.neu.edu)
Date: Thu Jun 3 10:36:51 EDT 2010

On Jun 3, 2010, at 10:32 AM, Eric Tanter wrote:

> Hi,
> I'm wondering what happens exactly when one "runs" a redex module that has no tests/traces at all.

Nothing really. See below. 

> I have one language definition and one reduction relation (admittedly both quite complex, around 300 lines with generous indentation), and when I click "run" it takes around 40 seconds before I get the prompt back in the interaction window. 
> So something substantial must be going on, I'd like to know what. 

Expansion. Redex is kind of like Typed Scheme in this regard. It exists to make your programs run slower. 

> In particular, that computation was able to find places where I forgot to use ellipsis for instance, but not able to report parts where I use undefined metafunctions (I use around 20 as-yet-undefined metafunctions in the reductions). I doubt that these 40 seconds are only used to check for proper uses of ellipses...
> (I'm on 4.2.5, mac os 10.6)
> Thanks!
> -- Éric
> _________________________________________________
>  For list-related administrative tasks:
>  http://list.cs.brown.edu/mailman/listinfo/plt-scheme

Posted on the users mailing list.