At this point it is an oversight.
> On Nov 21, 2015, at 6:51 AM, Paolo Giarrusso <[email protected]> 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 [email protected]. > 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 [email protected]. For more options, visit https://groups.google.com/d/optout.
