Good to understand the trade-off. In a similar vein I see that in BSL (+ ...), for example, requires at least two arguments vs zero or more in racket.
I did find it a little odd that I had recourse to use a "teachpack" to gain access to this nice set of general-purpose drawing abstractions. Are the facilities provided in 2htdp/image used a fair bit in non-teaching contexts? If so, would it make sense to factor out a racket-oriented library at some stage? Dan On Tue, Oct 22, 2013 at 5:33 AM, Matthias Felleisen <matth...@ccs.neu.edu>wrote: > > This is of course a symptom of the more general problem that we fail to > have a mechanism that specializes a module to a particular language > context. In *SL, the restriction is absolutely great; in Racket, the > restriction is a pain. Note that units wouldn't solve the problem cleanly > either -- Matthias > > > > > > > > On Oct 22, 2013, at 8:14 AM, Robby Findler <ro...@eecs.northwestern.edu> > wrote: > > > I did this explicitly because (I believe) it helps with parenthesis > errors when beginning students make simple mistakes using the library. For > more advanced programmers, it seems straightforward to define things like: > > > > (define (above* . is) (cond [(null? is) (blank)][(null? (cdr is)) (car > is)][else (apply above is)]) > > > > and you can even abstract that as a function that takes something like > above and builds an above* from it. > > > > Robby > > > > > > On Mon, Oct 21, 2013 at 10:58 PM, Daniel Prager < > daniel.a.pra...@gmail.com> wrote: > > Currently above from 2htdp/image requires at least two arguments. I.e. > > > > procedure > > (above i1 i2 is ...) → image? > > > > Recently I have been using an idiom where I stack a list of one or more > images. > > I.e. > > > > (apply above list-of-images) > > > > I have a workaround, but it seems to me that a more tolerant "above" -- > which acts as an identity when passed a single image -- would be an > improvement to the > > library. > > > > Similarly for beside, etc. > > > > > > Dan > > > > ____________________ > > Racket Users list: > > http://lists.racket-lang.org/users > > > > > > ____________________ > > Racket Users list: > > http://lists.racket-lang.org/users > > -- *Daniel Prager* Agile/Lean Coaching, Software Development and Leadership Twitter: @agilejitsu <https://twitter.com/agilejitsu> Blog: agile-jitsu.blogspot.com
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