[racket-dev] patch for make-base-eval

From: Ryan Culpepper (ryanc at ccs.neu.edu)
Date: Wed Oct 2 15:37:15 EDT 2013

On 10/02/2013 03:19 PM, Stephen Chang wrote:
> Can I push the attached (1-line) patch? I don't have a good grasp of
> namespaces so I would like someone to review it first.
> Right now, make-base-eval tries to attach racket/pretty to the
> namespace regardless of whether it's already there, which sometimes
> results in an exception (for example if the #lang given to
> make-base-eval is racket).
> The patch simply first checks if the desired identifier is already there.

Whether that identifier exists in the namespace has nothing to do with 
whether racket/pretty can be attached.

One option would be for install-pretty-printer! to just catch and 
discard the error. Evaluators for some languages would mysteriously not 
have pretty-printing turned on by default.

Another option would be to attach racket/pretty before requiring the 
initial language for the namespace.

Another option is use #:pretty-print? #f when attaching racket/pretty 
would fail.


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