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> </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. <div> </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> ). <div> </div><div>Robby On Monday, July 21, 2014, Matthew Butterick <<a href="mailto:mb@mbtype.com">mb@mbtype.com</a>> wrote: <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 > that case appears to be what you're seeing. Is that what you're > getting? Your theory seems correct. Yes, Pollen is the only #lang returning #f for read-language, e.g.: #lang racket/base (map (λ(lang) (read-language (open-input-string (format "#lang ~a" lang)))) '(racket racket/base scratchy scribble/manual scribble/text rackjure pollen)) '(#<procedure:language-info> #<procedure:language-info> #<procedure:...atchy/reader.rkt:26:2> #<procedure:language-info> #<procedure:language-info> #<procedure:language-info> #f) Moreover, if I use your main.rkt, it triggers the same problem in DrRacket (#lang line is red, no toolbar buttons) 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: #lang racket/base (require pollen/main-base) (define+provide-module-begin-in-mode world:mode-preproc) (module reader racket/base (require pollen/reader-base) (define+provide-reader-in-mode world:mode-auto)) ... 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. 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? 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: > It appears that read-language can return #f and what DrRacket does in > that case appears to be what you're seeing. Is that what you're > getting? > > The docs say that read-language never returns #f (presumably it is > allowed to return #f when fail-thunk returns #f, but the relevant > fail-thunk here doesn't return #f) so I'm not sure if that's a docs > bug, in which case I should change drracket to cope with it or an > implementation bug. > > But if I create a pollen directory, use 'rack pkg --link pollen' to > set it up and then put main.rkt with this content: > > #lang racket/base > (module reader racket/base (provide read-syntax) > (define (read-syntax a b) > #'(module m racket/base))) > > then I see this: > > $ racket > Welcome to Racket v6.1.0.3. >> (read-language (open-input-string "#lang pollen")) > #f > > > Robby ____________________ Racket Users list: <a href="http://lists.racket-lang.org/users" target="_blank">http://lists.racket-lang.org/users</a> </blockquote></div></div></div>