Racket is not a language, it is a collection of languages (MHO) I am very pleased with the #lang or #!... line on top of my modules. I must admit that I run all of my programs under control of DrRacket, although I don't have much problems running my programs by means of Gracket.exe nor by making executables (which may, of course, require the correct mode of making the executable) I think we have to accept that Racket is not Scheme (It does include R6RS, but I prefer #lang racket, which no longer is a small language, but still can be used as though it were a small language) Jos
> -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Stephen Bloch > Sent: 15 May 2011 15:36 > To: Racket Users > Subject: Re: [racket] #lang > > Eli writes: > > >> I'd rather have my > >> students' files start with > >> #lang bsl > >> or > >> #lang isll > >> or something, as long as my students don't need to SEE that. > > > > -1. > > I presume the part you don't like is "my students don't need > to SEE that"? > > I'm not suggesting that the choice of language should be > invisible and inaccessible, only that the #lang syntax should > be invisible much (if not all) of the time. > > For example, there might be a display near the top of the > DrRacket window saying at all times what language we're in, > without the word "#lang". If you want to change it, you > click on that display and type in a new language choice, > still without the word "#lang". If it's not recognized, you > get an immediate error message. The language choice menu, if > it still exists, would be just a shortcut for filling in one > of several guaranteed-to-exist languages. You NEVER see the > #lang line in the Definitions pane. > > >> Could we have a menu option in DrRacket to hide or show the #lang > >> line (perhaps in a separate pane)? > > > > -1. > > > > As Shriram said, this is similar to how the language choice > is encoded > > in current teaching language files, and it leads to bad surprises -- > > weird errors if you do add a `#lang' in the part that you do see > > That's a simple syntax error: "#lang blah" isn't legal syntax > inside a module, in any language that I know of. One could > give it a clear, informative error message: in racket, "You > have two #lang lines in the same source file," and in > DrRacket, something like "You've already specified the > language in the language display at the top of the window". > > However, people are much less likely to put a "#lang" into > the part that they do see if they've never seen the word > "#lang", as would be true of DrRacket-using students. Those > that use a vanilla text editor can clearly see that they've > got two of them. > > > surprises when you edit the file outside of DrRacket > > See above. > > > , and confusions when you copy-paste the code and send it > to someone else. > > Yes, copy-and-paste is a problem. If you copy-and-paste from > one DrRacket window into another, they both presumably have > (hidden) #lang lines, so things should be clear (either > they're in the same language and everything works, or they're > explicitly in different languages and you deserve what you > get). If you copy-and-paste from DrRacket into a text file > and then use that text file in racket or DrRacket, DrRacket > will have to use its default language (see below). > > >> For the benefit of beginning students, I'd like to keep > the language > >> selection menu, but its effect would be to alter the (hidden) #lang > >> line. > > > > IME, the language dialog is currently a major source of > confusion. It > > tempts people to choose languages that they shouldn't choose > > I'm not wedded to it myself, but I think it can be clearer > and more transparent than it is now. I'm suggesting getting > rid of "Use the language declared in the source", because > that would ALWAYS be true. The menu, if it continues to > exist, would be just shortcuts to some suggested languages. > And if everything on this menu can also be invoked from > #lang, that list could be trimmed down to only the ones used > by significant numbers of beginners: say, the HtDP and > DeinProgramm teaching languages and racket. > > The one UI drawback to this proposal (that I see) is that if > one is currently in a language that isn't on the menu, > nothing in the menu would be checked. One could switch from > it to a "standard" language using the menu but wouldn't be > able to get back using the menu; you'd need to click the > language display and type in the language name. However, > this would only affect people already using a language that's > not in the menu, which means they must have used the manual > override before, and they should be able to use it again. > > > BTW, to put these negatives in more perspective -- a *lot* > of work has > > been put to make the `#lang' lines very simple -- easy to remember, > > and easy to write. So I view removing them from the user's explicit > > reach and instead leaving it for some gui to generate as something > > that goes against the whole idea of `#lang'. > > Shriram writes: > > If you really wanted to accommodate all comers, > > > > - no #lang => language is BSL > > - all other languages need their own #lang line > > Yes, that makes some sense. Philosophically, one would > rather have the default language be racket -- I can imagine > the howls of protest from somebody like Elliott who starts up > racket or DrRacket, types in the first example from some > non-HtDP Scheme book, and gets an error message because it's > not in BSL. But as a teacher, I'd want BSL to be extremely > easy to get to. > > > (Of course I'm glossing over the #lang bsl =/= BSL from > menu, which is > > a real annoyance.) > > How much difference is there? Can we fix it? > > > > Stephen Bloch > [email protected] > > > _________________________________________________ > For list-related administrative tasks: > http://lists.racket-lang.org/listinfo/users _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
