[plt-scheme] Semantics of quote

From: Carl Eastlund (cce at ccs.neu.edu)
Date: Mon Jun 23 19:10:01 EDT 2008

On Mon, Jun 23, 2008 at 6:57 PM, Aleks Bromfield <aleks at cs.brown.edu> wrote:
> On Mon, Jun 23, 2008 at 04:06:55PM -0400, Matthias Felleisen wrote:
>> The sad thing is that this is needlessly confusing, especially for
>> beginners. It is one of the reasons we have teaching languages that
>> (1) don't allow quote for anything but symbols (pop quiz: is ''a a
>> symbol?) and (2) renders things as constructed values (think abstract
>> or universal algebra, if you're familiar with that).
> Out of curiosity, why isn't constructor-style printing the default for
> the module language as well?

One reason is that there's no way to know what the constructors "look
like" in the user's language.  They could be named anything; the
language's syntax may even vary from Scheme.  Student languages are
simpler; all the constructors are known ahead of time.

A given language can always set up a custom printer based on its own
constructors, but DrScheme can't do that automatically.

Carl Eastlund

Posted on the users mailing list.