[plt-scheme] Help with #0 and #0# notation in the REPL

From: Robby Findler (robby at cs.uchicago.edu)
Date: Mon Jan 28 23:14:35 EST 2008

On Jan 28, 2008 10:11 PM, Aleks Bromfield <aleks at cs.brown.edu> wrote:
> On Mon, Jan 28, 2008 at 09:36:32PM -0600, Robby Findler wrote:
> > Altho in v4, the input/output pair that match are read/write and the
> > input we use for code isn't read, but read-syntax.
> >
> > In less obscure wording, v4 does not support the #0= notation for
> > constants in programs. You'd have to build the data structure at
> > runtime, or use `shared' (or similar).
> Why was this change made?

It simplifies the compiler and tools that operate on program source if
there are no cycles in what they have to process (it isn't a normal
thing to think about that a program's AST is cyclic!) and so we
decided to experiment with leaving it out. We do still support cycles
in general, of course, so maybe less is gone than you might think.
Give it a try!


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