At this point it is an oversight.
> On Nov 21, 2015, at 6:51 AM, Paolo Giarrusso <p.giarru...@gmail.com> wrote: > > list? is not available [1] in either BSL or BSL with list abbreviations. Why? > Lists are used everywhere even in BSL, and `list?` literally appears in half > its documented contracts in beginner docs [2] — how should students > understand them? > > I've looked for reasons, to no avail. I've only learned that: > - unlike in Racket, the disjunction of `cons?` and `empty?` would be enough > to redefine `list?`, since improper lists are forbidden > - HtDP/2e doesn't mention `list?` in the chapter on lists [3], even though it > comes after the chapter where "sum types" (ahem, itemizations) are introduced. > > [1] Racket rejects `(list? empty)` with "list?: this function is not defined" > [2] http://docs.racket-lang.org/htdp-langs/beginner.html > [3] http://www.ccs.neu.edu/home/matthias/HtDP2e/Draft/part_two.html > [4] http://www.ccs.neu.edu/home/matthias/HtDP2e/Draft/part_one.html > > -- > You received this message because you are subscribed to the Google Groups > "Racket Users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to racket-users+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
