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

From: Matthias Felleisen (matthias at ccs.neu.edu)
Date: Mon Jan 30 16:14:13 EST 2012

On Jan 30, 2012, at 4:11 PM, Sam Tobin-Hochstadt wrote:

>  Perhaps it should just have less information.

I like that a lot. 

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