Not as long as "." is legal in the middle of an identifier: > (define a.b 3) > a.b 3
On Wed, Aug 18, 2010 at 12:09 PM, Matthias Felleisen <matth...@ccs.neu.edu> wrote: > > Nice idea. I second that. > > > On Aug 18, 2010, at 11:14 AM, Jay McCarthy wrote: > >> This is a price you are already paying in Typed Racket. I'd like to see more >> ways of putting types to work implemented. >> >> Jay >> >> Sent from my iPhone >> >> On Aug 18, 2010, at 8:52 AM, Matthias Felleisen <matth...@ccs.neu.edu> wrote: >> >>> >>> Eduardo is providing a macro that helps you abbreviate complex >>> selector and mutator chains. The BENFIT you get is that instead >>> of writing >>> >>> (posn-x (bird-posn (sky-bird (world-sky some-world)))) >>> >>> you can write -- in Racket -- >>> >>> some-world.sky.bird.posn.x >>> >>> and make Racket programs look as short as C program selectors >>> or Java dots or Javascript dots etc. >>> >>> The PRICE you pay is that you annotate variables and fields >>> with struct information. That is, you have to say somewhere that >>> some-world is a variable that always stands for a world struct. >>> And the sky field in world has to come with information that it >>> always is a sky-struct. And so on. >>> >>> ;; --- >>> >>> To make this available in Racket, you'd have to port his macros >>> from R6RS Scheme to Racket. I suspect that this would be a minor >>> task. >>> >>> ;; --- >>> >>> To make this available in the teaching languages, you'd have to >>> export these macros in a way that makes sense for students. Or >>> you keep it all private to yourself. >>> >>> ;; --- >>> >>> I assume that you understand the differences between the various >>> operations. In Java, >>> >>> pos.draw >>> >>> comes with static knowledge about pos (an object of a certain type) >>> and draw (a field of a certain type) that is exploited to make the >>> notation short and safe. It isn't complete safe because of NULL, >>> which doesn't exist in Racket or the teaching languages, but let's >>> ignore that. >>> >>> In a language like Ruby, >>> >>> pos.draw >>> >>> just doesn't care, If pos has an draw field at run-time, good enough. >>> Even if pos isn't a position but happens to have a draw field, just >>> keep on computing. >>> >>> In Racket and the teaching languages, you are *forced* to write >>> down what kind of struct you expect and what field you want: >>> >>> pos.check-it-is-a-posn-and-select-x-then >>> >>> This gives you safety a la Java (at run-time) and tells the reader >>> at each site where you write down a selector expression what you >>> expect. It's verbose but readable. >>> >>> >>> >>> >>> On Aug 18, 2010, at 10:34 AM, Mathew Kurian wrote: >>> >>>> >>>> >>>> On Wed, Aug 18, 2010 at 2:41 AM, Eduardo Cavazos <wayo.cava...@gmail.com> >>>> wrote: >>>> >>>> Mathew Kurian: >>>> >>>> However, in the case of universe/world teachpacks, where the use of >>>> states is a vital component, a set of code can get very long, >>>> especially if the program is very complex and contains multiple >>>> structures (in some cases structures inside structures inside >>>> structures) within the states. >>>> >>>> I agree with the critique of lengthy expressions involving nested records >>>> (structs). >>>> >>>> Here's how I deal with it: >>>> >>>> http://gist.github.com/364754 >>>> >>>> The particular solution is for R6RS but PLT has the necessary mechanisms >>>> for it. >>>> >>>> Ed >>>> >>>> Hey Ed, >>>> >>>> If you have spare time, can you please explain by what you meant in that >>>> github website. All I saw was a comparison between C and Scheme. >>>> >>>> Thank you >>>> >>>> Mathew K. >>>> >>>> >>>> _________________________________________________ >>>> For list-related administrative tasks: >>>> http://lists.racket-lang.org/listinfo/users >>> >>> _________________________________________________ >>> For list-related administrative tasks: >>> http://lists.racket-lang.org/listinfo/users > > _________________________________________________ > For list-related administrative tasks: > http://lists.racket-lang.org/listinfo/users > _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
