<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div>I can confirm that when I add a get-info function to the Pollen reader, it does work as expected in DrRacket. So perhaps Pollen doesn't "need" to change, but it will ;) Thank you for the help.</div><div><br></div><div>FWIW here's the accumulation of stumbles that led to my mistake:</div><div><br></div><div>+ AFAICT the #lang tutorial in the docs refers to get-info but not read-language. [1] Thus I never knew that read-language existed or what it did.</div><div><br></div><div>+ Based on the tutorial example [1], I had incorrectly concluded that get-info was an arbitrary private name, rather than a special name sought by read-language. </div><div><br></div><div>+ I also didn't appreciate that get-info is mandatory for proper DrRacket compatibility, not optional.</div><div><br></div><div>+ (get-info, of course, is also the name of a function in setup/getinfo [2])</div><div> </div><div>+ When there is no get-info function, DrRacket visually suggests that an error has occurred (red #lang line, no toolbar buttons) but doesn't print the actual error in the window (creating mystery)</div><div><br></div><div>+ You say that DrRacket doesn't cache any #lang information at startup. For whatever reason, I continue to find that relaunching makes a difference (i.e., if the #lang doesn't provide get-info at the beginning of a DrRacket session, adding one *during* the session will not fix the error; it will be noticed only on relaunch). I can't account for this behavior, but I can reliably reproduce it. This issue tripped me up, however, as it made it seem that get-info was not making a difference, so I eliminated it as the solution too soon.</div><div><br></div><div><br></div><div><br></div><div>[1] <a href="http://docs.racket-lang.org/guide/language-get-info.html?q=#lang&q=read-language">http://docs.racket-lang.org/guide/language-get-info.html?q=%23lang&q=read-language</a></div><div><br></div><div>[2] <a href="http://docs.racket-lang.org/raco/getinfo.html?q=get-info&q=#lang&q=read-language#(def._((lib._setup/getinfo..rkt)._get-info))">http://docs.racket-lang.org/raco/getinfo.html?q=get-info&q=%23lang&q=read-language#%28def._%28%28lib._setup%2Fgetinfo..rkt%29._get-info%29%29</a></div><div><br></div><div><br></div><br><div><div>On Jul 20, 2014, at 6:21 PM, Robby Findler <<a href="mailto:robby@eecs.northwestern.edu">robby@eecs.northwestern.edu</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">Yeah: I think that it is safe to say at this point that pollen doesn't need to change. Either read-language's docs (and various places in DrRacket and libraries) need to change or read-language needs to change and either way pollen will work afterwards. <div> <br></div><div>My guess is that your language is the only one that doesn't define a get-info function itself but I can't check that theory right now. <br><div><br></div><div>You can probably make pollen work now by supplying a get-info proc that always returns the default value. (See the third and subsequent paragraphs here: <a href="http://docs.racket-lang.org/reference/Reading.html?q=read-language#%28def._%28%28quote._~23~25kernel%29._read-language%29%29">http://docs.racket-lang.org/reference/Reading.html?q=read-language#%28def._%28%28quote._~23~25kernel%29._read-language%29%29</a> ).<br> <div><br></div><div>Robby<br><br>On Monday, July 21, 2014, Matthew Butterick <<a href="mailto:mb@mbtype.com">mb@mbtype.com</a>> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> > It appears that read-language can return #f and what DrRacket does in<br> > that case appears to be what you're seeing. Is that what you're<br> > getting?<br> <br> Your theory seems correct. Yes, Pollen is the only #lang returning #f for read-language, e.g.:<br> <br> #lang racket/base<br> (map<br> (λ(lang) (read-language (open-input-string (format "#lang ~a" lang))))<br> '(racket racket/base scratchy scribble/manual scribble/text rackjure pollen))<br> <br> '(#<procedure:language-info><br> #<procedure:language-info><br> #<procedure:...atchy/reader.rkt:26:2><br> #<procedure:language-info><br> #<procedure:language-info><br> #<procedure:language-info><br> #f)<br> <br> <br> Moreover, if I use your main.rkt, it triggers the same problem in DrRacket (#lang line is red, no toolbar buttons)<br> <br> But beyond the issue of whether the docs or DrRacket is doing the right thing with the #f value, I'm unclear why Pollen is returning #f for read-language. One possibly unorthodox thing I'm doing here is that my #lang files rely on macro expansion. For instance, here's Pollen's main.rkt:<br> <br> <br> #lang racket/base<br> (require pollen/main-base)<br> (define+provide-module-begin-in-mode world:mode-preproc)<br> <br> (module reader racket/base<br> (require pollen/reader-base)<br> (define+provide-reader-in-mode world:mode-auto))<br> <br> <br> ... where `define+provide-module-begin-in-mode` is a macro that creates the #%module-begin macro, and `define+provide-reader-in-mode` is a macro that creates the reader.<br> <br> This doesn't bother DrRacket when the file is being run, but perhaps this approach is incompatible with either read-language, or DrRacket's #lang validation?<br> <br> <br> <br> <br> <br> On Jul 20, 2014, at 4:50 PM, Robby Findler <<a href="javascript:;" onclick="_e(event, 'cvml', 'robby@eecs.northwestern.edu')">robby@eecs.northwestern.edu</a>> wrote:<br> <br> > It appears that read-language can return #f and what DrRacket does in<br> > that case appears to be what you're seeing. Is that what you're<br> > getting?<br> ><br> > The docs say that read-language never returns #f (presumably it is<br> > allowed to return #f when fail-thunk returns #f, but the relevant<br> > fail-thunk here doesn't return #f) so I'm not sure if that's a docs<br> > bug, in which case I should change drracket to cope with it or an<br> > implementation bug.<br> ><br> > But if I create a pollen directory, use 'rack pkg --link pollen' to<br> > set it up and then put main.rkt with this content:<br> ><br> > #lang racket/base<br> > (module reader racket/base (provide read-syntax)<br> > (define (read-syntax a b)<br> > #'(module m racket/base)))<br> ><br> > then I see this:<br> ><br> > $ racket<br> > Welcome to Racket v6.1.0.3.<br> >> (read-language (open-input-string "#lang pollen"))<br> > #f<br> ><br> ><br> > Robby<br> <br> <br> ____________________<br> Racket Users list:<br> <a href="http://lists.racket-lang.org/users" target="_blank">http://lists.racket-lang.org/users</a><br> </blockquote></div></div></div> </blockquote></div><br></body></html>