[racket] constructing a boolean that's a filter for a given type? could be automatic?

On Mon, Jan 30, 2012 at 4:04 PM, Matthias Felleisen
<matthias at ccs.neu.edu> wrote:
>
> And what do you say to this:
>
>> I admit that that error just makes my eyes glaze over, but I'm pretty sure that the problem here is that TR can't reduce this filter type, and just needs a cleverness injection.

Unfortunately, I don't know how to explain this error message
usefully.  Perhaps it should just have less information.
-- 
sam th
samth at ccs.neu.edu