Hello, If I put this R6RS library: #!r6rs (library (xyz abc) (export abc) (import (rnrs)) (define abc 10)) in the file '~/scheme/xyz/abc.sls', Racket can find it. However, if I put this library: #!r6rs (library (abc) (export abc) (import (rnrs)) (define abc 10)) in the file '~/scheme/abc.sls', Racket doesn't seem to find it.(Continue reading)
On Tue, Nov 30, 2010 at 05:56:08PM -0600, Eduardo Cavazos wrote: > Hi Matthias, > > On Wed, 2010-08-18 at 10:52 -0400, Matthias Felleisen 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. This looks as if it might be a better match with Typed Scheme/Racket. -- hendrik
Hi Matthias, > It isn't clear to me whether you have tried > > > (help "lambda") > > in your emacs repl. If so, do you object to the browser coming up with intensively hyperlinked documentation? Or do you not like the format? (Evidently I had not. Now that is embarrassing. I could swear I had tried it before, maybe back when I just had the PLT Scheme packages installed, with only an unbound name error as the result...Is this perhaps a recent addition? Or could I have inadvertently done some configuration that makes "help" available in my Racket REPL when it wasn't before?) > Let us know what's wrong with that. There's nothing wrong with it; it's great! Thanks for pointing this out to me. If I had my druthers, the help function would also be a tool for introspection. (Is there another function designed for this? (help "introspection") doesn't turn up any results... :) [See examples below] But I realize that this may be asking for precisely the kind of REPL interaction that Racket has consciously chosen to avoid. > I have done a lot of bottom up programming in Emacs (Scheme and Lisp) and I still do in DrRacket. But I learned that bottom-up programming is the norm and that what makes it successful is some amount of top-down planning. If you meet somewhere in the middle and explore from there, you can grow into a(Continue reading)
On Nov 30, 2010, at 10:07 PM, Richard Lawrence wrote: > If I had my druthers, the help function would also be a tool for > introspection. Programs are either throw away or deserve a full-fledged, indexed documentation. Is Python's documentation properly (scoped) hyperlinked? -- Matthias
I think something like this has come up before but I can't find the
thread. Given:
(define A%
(class object% (inspect #f) (super-new)))
(define/contract B%
(class/c )
(class object% (inspect #f) (super-new)))
How can I get around the problem that:
(equal? (new A%) (new A%))
but
(not (equal? (new B%) (new B%)))
I want to be able to compare objects of the same contracted class for
structural equality.
And another question: is there something similar to struct-copy for
objects? Or a way to easily clone them?
--- nadeem
9 hours ago, prad wrote: > > i like the incremental search system for the documentation, though > it doesn't have an apropos feature like emacs. The incremental search can be used more effectively as a kind of apropos if you limit the search to a specific module, for example searching for "cons M:racket" will show you only matches that are bindings from a module that has "racket" in its name. But if you want a more traditional repl apropos feature, see my interactive hack -- it has an ,apropos command. Three hours ago, Richard Lawrence wrote: > > It isn't clear to me whether you have tried > > > > > (help "lambda") > > > > in your emacs repl. If so, do you object to the browser coming up > > with intensively hyperlinked documentation? Or do you not like the > > format? BTW, if you tried just that, then note that you can also an identifier to jump directly to its definition: (help lambda) This uses the *syntactic* information from the system, for example: (define kons cons)(Continue reading)
On Dec 1, 2010, at 1:20 AM, Eli Barzilay wrote: >> >> Examples: comparing Python's help function to Racket's as a tool for >> introspecting objects at the REPL >> [...] >>> (define (f x y) >> (+ x y)) >>> (help f) >> Not found in any library's documentation: f > > This is because you didn't document it. I wonder whether help could display contracts if the module use provide/contract to export f.
On Nov 30, 2010, at 10:32 PM, Nadeem Abdul Hamid wrote: > I think something like this has come up before but I can't find the > thread. Given: > > (define A% > (class object% (inspect #f) (super-new))) > (define/contract B% > (class/c ) > (class object% (inspect #f) (super-new))) > > How can I get around the problem that: > (equal? (new A%) (new A%)) > but > (not (equal? (new B%) (new B%))) > > I want to be able to compare objects of the same contracted class for > structural equality. This is indeed a problem with the current implementation of class/c. I'm currently working on reimplementing parts of our contract system to take advantage of the new chaperone and impersonator wrappers. Once class/c is rewritten, I believe that this problem will just go away, since all the information about which inspectors have access (or that all inspectors have access, in this case) should be preserved. Feel free to submit a bug in the meantime, so that I'll have a reminder to check that this has indeed been solved once I've finished. > And another question: is there something similar to struct-copy for > objects? Or a way to easily clone them? No, though this has been a requested feature before; I know that Ryan has done some work in this area before, but I haven't had a chance at incorporating what he's done, or something similar, into the core class(Continue reading)
Hi all -
<div> <p>Hi all - </p> <div><br></div> <div>a question for those who have experiences with metacircular interpreters: </div> <div><br></div> <div>How do you represent the lexical variables? Since lexical variables can be optimized away so they won't show up on a call to eval, it seems putting them into the environment (I am using a struct holding an immutable hash for environment) isn't the right approach. It feels like I need my own call-stack to represent them, but that sounds "heavy" for a metacircular interpreter. </div> <div><br></div> <div>Any thoughts are appreciated, thanks. </div> <div>yc</div> <div><br></div> <div><br></div> </div>
> > On Dec 1, 2010, at 1:20 AM, Eli Barzilay wrote: > >>> >>> Examples: comparing Python's help function to Racket's as a tool for >>> introspecting objects at the REPL >>> [...] >>>> (define (f x y) >>> (+ x y)) >>>> (help f) >>> Not found in any library's documentation: f >> >> This is because you didn't document it. Yes, right. This was perhaps not the best illustration. I don't think it would be terribly useful to read documentation (per se) about functions defined at the REPL. I meant to illustrate that calling help on a procedure object in Python gives you a certain amount of information (regardless of whether the author has documented it or not), including the module it is defined in and its required and optional arguments. Is there a way to get this kind of information in Racket at the REPL, regardless of whether or not the author has been scrupulous in documenting her work? > I wonder whether help could display contracts if the module use > provide/contract to export f. This is exactly the kind of thing I would find useful. Or perhaps I should say: it is the kind of thing I have found useful in the past. The spirit of my original question was meant to be: given that I found this useful in the past, what's the right way of translating that experience to programming in Racket? Should I be looking for a way to do similar things in Racket, or should I be revising the way I think about and use the documentation system? It seems like the answer is, "both." Best, Richard
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