I think the plan is to change pconvert so that it prints as `(foo 1 2)' by default (and then change the teaching languages to bring back the "make" prefixes).
Robby On Mon, Nov 21, 2011 at 6:50 AM, Jay McCarthy <jay.mccar...@gmail.com> wrote: > From your email below, Matthew, I get the impression that you think some of > this can't be fixed inside the PLAI language itself, because there's no > other option at the Racket level. Is that correct? > Jay > > On Sun, Nov 20, 2011 at 7:48 AM, Matthew Flatt <mfl...@cs.utah.edu> wrote: >> >> At Sun, 20 Nov 2011 09:31:02 -0300, Eric Tanter wrote: >> > By default, #lang plai prints out values as follows in the REPL: >> > >> > (define-type Foo >> > (foo (x number?))) >> > >> > > (foo 1) >> > (foo 1) >> > > (list 1 2) >> > '(1 2) >> > >> > The output is not really consistent, in that foo is printed as a >> > (user-level) >> > constructor, but list is not. >> >> Well, `quote' is playing the role of constructor. >> >> > For teaching, the problem with output '(1 2) is >> > the need to explain (or try to ignore) the quote. >> >> PLAI uses `quote' for lists starting on page 8, so if you're teaching >> with the book, it may not be worthwhile to avoid `quote'. >> >> I think my students has had little trouble with `quote'. In contrast, >> in the bad old days when the `quote' was missing --- so that `(list 1 >> 2)' printed as just `(1 2)' --- students had a difficult time with the >> difference between expressions and printed values. >> >> > If I change the output configuration to "constructor", then I get: >> > >> > > (foo 1) >> > (make-foo 1) >> > > (list 1 2) >> > (list 1 2) >> > >> > Now list is printed as constructor, but foo is printed using its >> > "low-level" >> > constructor, which for teaching is not that great either. >> >> Agreed --- this should be fixed. >> >> Currently, constructor-style printing always uses a "make-", but the >> default mode should be to use the same constructor name that `print' >> uses when `print-as-expression' is true. >> >> > The other option for output is "write", which gives: >> > >> > > (foo 1) >> > #(struct:foo 1) >> > > (list 1 2) >> > (1 2) >> > >> > Again not so nice. >> >> Agreed --- definitely not the right option for teaching. >> >> > Basically, there seems to be no way to obtain: >> > >> > > (foo 1) >> > (foo 1) >> > > (list 1 2) >> > (list 1 2) >> > >> > Is there? >> >> Right -- not until we fix constructor-style printing. >> >> _________________________________________________ >> For list-related administrative tasks: >> http://lists.racket-lang.org/listinfo/users > > > > -- > Jay McCarthy <j...@cs.byu.edu> > Assistant Professor / Brigham Young University > http://faculty.cs.byu.edu/~jay > > "The glory of God is Intelligence" - D&C 93 > > _________________________________________________ > For list-related administrative tasks: > http://lists.racket-lang.org/listinfo/users > _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
