Re: surprising [to me and students] printer behavior with #:transparent

Ah, got it, makes perfect sense through that lens -- thanks!

On Tue, May 16, 2017 at 9:37 AM, Philip McGrath <philip-HuI0B06iylScIzJqBAPImwC/[email protected]>
wrote:

> The printer tries to produce an expression that you could copy, paste, and
> evaluate. Transparent structs aren't quotable but do support
> constructor-style printing, so the printer uses constructor-style printing
> for values that contain transparent structs. (Apparently you can configure
> this in DrRacket to use e.g. quasiquotation if you prefer:
> https://docs.racket-lang.org/drracket/output-syntax.html) Since opaque
> structs don't support any nice printing behavior by default, the printer
> gives up and uses the more concise quoted form with the non-expression
> printed form of the opaque value.
>
> The docs for prop:custom-print-quotable and gen:custom-write and the
> Reference section on The Printer
> <https://docs.racket-lang.org/reference/printing.html> have more
> technical details.
>
> On Tue, May 16, 2017 at 9:21 AM, Dan Grossman <[email protected]>
> wrote:
>
>>
>> Hi all,
>>
>> In my course here on campus, I have students use #lang racket and we put
>> #:transparent on our struct definitions for easier REPL interactions.  A
>> student was confused by the different printer-behavior between a and b in
>> the attached screenshot, and I can't think of a reason for the different
>> behavior for b compared to a and c either.  Curious if there /is/ a decent
>> reason or if this is just one of those glitches.
>>
>> "No big deal" but worth asking...
>>
>> [image: Inline image 1]
>>
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>

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