This is exactly what Shoes 4 is. We're taking advantage of JRuby to handle this for us. Packaging was a huuuuuuuge question here.

> Just implement Hackety Hack as an offline web app, where the typed Ruby code is just piped to the interpreter running on the box, and the results are returned as HTML displayed in the browser?

I think the biggest thing that you're not appreciating here is how many dependencies there are and how they combine: this would not include Ruby. Or any of the libraries that work with it. Then we'd have to re-write all of the GUI code to be in-browser instead of the existing render to screen stuff.

> It seems like a lot of work is reinventing basic things

First rule of legacy code: You can't replace it all at once. This stuff takes time.

Telling one person "Can't you _just_ re-implement Mac/Windows/Linux GUI stuff (optionally re-writing it all in browser, of course) with embedded Ruby, write the app on top of it, make a website, write curriculum, promote it, and everything else?" is a bit... much, eh?

(oh, funny bit of history: Shoes was actually embedded Gecko long before it was a native GUI toolkit. but that's a story for another time...)

To give you an idea of size:

    steve at thoth in ~/src/shoes on develop
    $ cloc .
         367 text files.
         358 unique files.                                          
         613 files ignored.

    http://cloc.sourceforge.net v 1.56  T=2.0 s (150.5 files/s, 38339.5 lines/s)
    --------------------------------------------------------------------------------
    Language                      files          blank        comment           code
    --------------------------------------------------------------------------------
    C                                80           5749           2184          41915
    Ruby                            127           1471           1588          10045
    C/C++ Header                     66            890            825           4165
    make                             12            375             36           2046
    Objective C                       3            151             15           1845
    Bourne Shell                      4            168             68            877
    Perl                              1            213            503            731
    YAML                              3            156              0            249
    CSS                               1              2              2            167
    Javascript                        2             26             38            150
    Bourne Again Shell                2              3              3             23
    --------------------------------------------------------------------------------
    SUM:                            301           9204           5262          62213
    --------------------------------------------------------------------------------


    steve at thoth in ~/src/hacketyhack on master
    $ cloc .
          75 text files.
          75 unique files.                              
          45 files ignored.

    http://cloc.sourceforge.net v 1.56  T=1.0 s (64.0 files/s, 6483.0 lines/s)
    -------------------------------------------------------------------------------
    Language                     files          blank        comment           code
    -------------------------------------------------------------------------------
    Ruby                            62            735            471           5260
    YAML                             2              1              0             16
    -------------------------------------------------------------------------------
    SUM:                            64            736            471           5276
    -------------------------------------------------------------------------------

    steve at thoth in ~/src/hackety-hack.com on master
    $ cloc .
         205 text files.
         198 unique files.                                          
         598 files ignored.

    http://cloc.sourceforge.net v 1.56  T=1.0 s (94.0 files/s, 2411.0 lines/s)
    -------------------------------------------------------------------------------
    Language                     files          blank        comment           code
    -------------------------------------------------------------------------------
    Ruby                            81            383            430           1219
    HTML                             3              7              1            114
    YAML                             6              8             25             90
    CSS                              1              7             40             47
    Javascript                       2              0              9             28
    CoffeeScript                     1              0              3              0
    -------------------------------------------------------------------------------
    SUM:                            94            405            508           1498
    -------------------------------------------------------------------------------

    steve at thoth in ~/src/hackety_hack-lessons on master
    $ cloc .
          14 text files.
          14 unique files.                              
          43 files ignored.

    http://cloc.sourceforge.net v 1.56  T=0.5 s (8.0 files/s, 292.0 lines/s)
    -------------------------------------------------------------------------------
    Language                     files          blank        comment           code
    -------------------------------------------------------------------------------
    Ruby                             4             24             10            112
    -------------------------------------------------------------------------------
    SUM:                             4             24             10            112
    -------------------------------------------------------------------------------