Yes. Also, it's not enough to check that 'racket/pretty' (or really, the
name 'racket/pretty' resolves to) isn't declared in the target
namespace; you must also check any module it (transitively) requires is
either undeclared or was attached from the same namespace you want to
attach racket/pretty from.
Ryan
On 10/02/2013 03:50 PM, Robby Findler wrote:
A namespace is a mapping from top-level identifiers to whatever they
are, as well as a separate mapping from module names to modules
(roughly). What you care about here is the second mapping, but you're
checking the first with the patch.
Robby
On Wed, Oct 2, 2013 at 2:45 PM, Stephen Chang <stch...@ccs.neu.edu
<mailto:stch...@ccs.neu.edu>> wrote:
> Whether that identifier exists in the namespace has nothing to do
with
> whether racket/pretty can be attached.
Can you explain this a little more because it's a little unintuitive
to me?
>
> 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.
>
> Ryan
>
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