[racket-dev] #true and #false

From: Matthew Flatt (mflatt at cs.utah.edu)
Date: Sat Oct 9 00:13:58 EDT 2010

At Fri, 8 Oct 2010 23:11:21 -0400, Eli Barzilay wrote:
> > This proposal originates with the need to fix a problem in the HtDP
> > teaching languages. The HtDP teaching languages currently use `true'
> > and `false' for true and false, and the HtDP languages are configured
> > to print booleans as `true' and `false'. That doesn't work with quoted
> > lists. For example,
> > 
> >   '(true false) 
> > 
> > is a list of symbols, not a list of booleans.
> BTW, wasn't the whole sophisticated quoted printout part of a solution
> to this, so that those true/false would not print out as quoted?

It's an expression issue, not a printing issue. We tell students that
`true' and `false' are literals, and we later tell them that `quote'
can be used to form lists of literals, and so they try to write the

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