Minggu, 30 November 2008
Rabu, 26 November 2008
Tips Bertanya di Kelas
Tips Bertanya di Kelas PMRI
Oleh: Dian Armanto
Di dalam kelas guru adalah instrumen pembelajaran yang utama, bukan sebagai pengantar materi semata ataupun penyaji utama pelajaran, melainkan sebagai fasilitator terjadinya aktivitas belajar di kelas. Sebagai fasilitator yang baik guru diharapkan memiliki keterampilan dasar mengajar (kompetensi) minimal seperti membuka dan menutup pelajaran, bertanya, memberi penguatan, mengadakan variasi pembelajaran, menjelaskan, membimbing diskusi, mengelola kelas, dan mengajar kelompok kecil. Keterampilan dasar ini merupakan keterampilan generik dan komplek yang harus dikuasai untuk menjadi guru dan perlu diintegrasikan ketika mengajar di kelas.
Tulisan ini mencoba memberikan beberapa tips untuk diujicoba guru di dalam kelas. Diharapkan contoh ini dapat membantu meningkatkan aktivitas belajar siswa di kelas. Selain itu juga diharapkan adanya peningkatan motivasi dan minat belajar siswa. Guru juga terbantu untuk menambah wawasan belajar dan pembelajaran di dalam kelas. Tips ini disarikan dari Workshop PMRI di beberapa kota yaitu Bandung, Surabaya, dan Yogya.
TIPS BERTANYA DI KELAS PMRI
* BERTANYA UNTUK MEMINTA PENJELASAN
Contoh:
Harap jelaskan jawabanmu.
Mengapa begitu?
* BERTANYA UNTUK MENCARI KLARIFIKASI
Contoh:
Siapa yang punya pertanyaan untuk Budi? Bagaimanakah pendapatmu tentang alasan Sugi?
* SAMPAIKAN PERTANYAAN KEPADA SEMUA ORANG
Contoh:
Siapa yang dapat menjawab pertanyaan Aminah?
* BERTANYA UNTUK MEMINTA PENDAPAT
Contoh:
Apakah kamu setuju dengan pendapat Ani?
* PASTIKAN SISWA MENDENGAR DAN PAHAM
Contoh:
Apakah kamu mendengar yang dikatakannya? Dapatkah kamu mengulangnya kembali?
(Prof Dr Dian Armanto, adalah dosen Universitas Negeri Medan (UNIMED))
Oleh: Dian Armanto
Di dalam kelas guru adalah instrumen pembelajaran yang utama, bukan sebagai pengantar materi semata ataupun penyaji utama pelajaran, melainkan sebagai fasilitator terjadinya aktivitas belajar di kelas. Sebagai fasilitator yang baik guru diharapkan memiliki keterampilan dasar mengajar (kompetensi) minimal seperti membuka dan menutup pelajaran, bertanya, memberi penguatan, mengadakan variasi pembelajaran, menjelaskan, membimbing diskusi, mengelola kelas, dan mengajar kelompok kecil. Keterampilan dasar ini merupakan keterampilan generik dan komplek yang harus dikuasai untuk menjadi guru dan perlu diintegrasikan ketika mengajar di kelas.
Tulisan ini mencoba memberikan beberapa tips untuk diujicoba guru di dalam kelas. Diharapkan contoh ini dapat membantu meningkatkan aktivitas belajar siswa di kelas. Selain itu juga diharapkan adanya peningkatan motivasi dan minat belajar siswa. Guru juga terbantu untuk menambah wawasan belajar dan pembelajaran di dalam kelas. Tips ini disarikan dari Workshop PMRI di beberapa kota yaitu Bandung, Surabaya, dan Yogya.
TIPS BERTANYA DI KELAS PMRI
* BERTANYA UNTUK MEMINTA PENJELASAN
Contoh:
Harap jelaskan jawabanmu.
Mengapa begitu?
* BERTANYA UNTUK MENCARI KLARIFIKASI
Contoh:
Siapa yang punya pertanyaan untuk Budi? Bagaimanakah pendapatmu tentang alasan Sugi?
* SAMPAIKAN PERTANYAAN KEPADA SEMUA ORANG
Contoh:
Siapa yang dapat menjawab pertanyaan Aminah?
* BERTANYA UNTUK MEMINTA PENDAPAT
Contoh:
Apakah kamu setuju dengan pendapat Ani?
* PASTIKAN SISWA MENDENGAR DAN PAHAM
Contoh:
Apakah kamu mendengar yang dikatakannya? Dapatkah kamu mengulangnya kembali?
(Prof Dr Dian Armanto, adalah dosen Universitas Negeri Medan (UNIMED))
Senin, 24 November 2008
BIlangan Bersahabat
Mencari pertemanan atau persahabatan melalui social networking mungkin sudah menjadi rutinitas sebagian dari kita. Tentu saja kesempatan itu kita lakukan agar semakin banyak " pertemanan atau persahabaatan" yang kita dapat dari dunia maya. Friendster, Face Book, My Space atau yang lainnya merupakan beberapa contoh dari social networking yang digemari oleh para peselancar di dunia maya. BTW, kalau
Minggu, 23 November 2008
Soal Minggu Ini 24112008
Sejumlah murid di suatu sekolah mengumpulkan uang sebanyak Rp. 960.000,-. Setiap murid harus memberi iuran yang sama. Kemudian ternyata ada 4 orang yang tidak dapat memberikan iuran karena alasan tertentu. Akhirnya untuk menutup kekurangannya, murid-murid lain harus menambah iurannya masing-masing Rp. 20.000,-. Berapah jumlah murid yang membayar?
Selamat Mencoba....
Selamat Mencoba....
Kamis, 20 November 2008
Pembahasan Integral 2
Pembahasan tentang materi integral yang saya bagi menjadi dua sesi ( yang pertama mengenai teknik pengintegralan ) memang belum sepenuhnya rampung atau diselesaikan. Tetapi daripada harus menunggu lebih lama lagi, karena memang ngga sempat / " ngga disempatkan ngerjainnya " akhirnya dengan terpaksa pembahasan yang baru setengah jadi ini saya upload juga. Tetapi meskipun pembahasannya baru
Rabu, 19 November 2008
"Blog"
Upaya Menjadi Lebih Dipercaya
Oleh PEPIH NUGRAHA
Sederhana saja mengukur penerimaan masyarakat atas blog di negeri ini. Tahun lalu, pada Pesta Blogger 2007, jumlah peserta hanya 500 orang. Kini, ketika Pesta Blogger 2008 kembali digelar, jumlah peserta yang terdaftar mencapai 1.200 orang. Jika tidak dibatasi, jumlahnya bisa jadi di atas 2.000 orang.
Memang parameter yang digunakan terlalu sederhana. Bukan maksud mengukur apakah blog diterima atau tidak oleh masyarakat, sebab hal itu tidak terlalu bermanfaat untuk dibahas. Lebih baik mengetahui bagaimana masyarakat memanfaatkan blog itu untuk berbagai keperluan, tidak sekadar bergaya atau asal punya blog. Maklum, sejak kelahirannya sampai kini blog masih dicibir banyak orang.
Padahal, dalam perkembangannya, blog ada yang mewujud sebagai citizen journalism, media indie yang menjadi bacaan alternatif. Dengan citizen journalism, siapa pun bisa memanfaatkan blog sebagai media penyampai pesan. Adagium ”media (blog) adalah pesan itu sendiri” menjadi terbukti di sini. Dan Gilmor dengan bukunya, We Media, mengklaim bahwa setiap orang adalah wartawan.
Kegiatan melaporkan suatu peristiwa dan menuliskannya pada media untuk disebarluaskan kepada khalayak bukan lagi milik jurnalis media arus utama. Warga bisa menjadi wartawan! Namun, tentu saja Gilmor mengatakan hal itu setelah tumbuh dan berkembangnya media online, web, dan kini blog yang bisa diperoleh secara mudah. Namun, karena mudahnya, blog didapat, ada anggapan bahwa ia tidak harus dipelihara dengan baik.
Dianggap tidak kredibel karena ulah segelintir blogger yang memanfaatkan blog untuk kepentingan sensasi belaka. Contoh ketika blog menjadi kontroversi dan dianggap sebagai penyebar fitnah setelah beredarnya rumor bahwa calon wakil presiden AS dari Partai Republik, Sarah Palin, tidak tahu Afrika merupakan benua. Rumor murahan ini ternyata berasal dari blog seseorang yang mengaku bernama Martin Eisenstadt.
Sayangnya, isu ini lalu ditangkap mentah-mentah media arus utama dan disiarkan tanpa berupaya melakukan cek dan ricek, meski pada akhirnya diralat.
Keterlibatan Amerika Serikat
Kalau begitu, apa yang harus dilakukan seorang blogger agar setiap posting-annya dapat dipercaya. ”Think before posting”, demikian pesan yang seharusnya ditangkap oleh setiap blogger sebelum menaruh tulisan dan gagasannya di blog. Apa yang di-posting-kan di blog harus menjadi tanggung jawab masing-masing blogger.
Wartawan senior harian ini, Ninok Leksono, pernah menulis di blog Kompasiana yang beralamat di http://kompasiana.com mengenai bagaimana seharusnya blog menjalankan fungsinya. Menurut dia, setiap pemilik blog berkepentingan agar blog miliknya tetap kredibel dan dipercaya warga pembaca lainnya. Bahkan, untuk Indonesia, katanya, ”Kredibilitas masih perlu ditambah dengan kearifan.”
Kembali ke Pesta Blogger 08 yang kali kedua ini digelar di Auditorium Gedung BPPT II Jakarta, Sabtu (22/11), ini menjadi sebuah pesta yang layak disimak. Bukan karena berkumpulnya komunitas blogger secara masif di sana, tetapi karena keterlibatan Pemerintah Amerika Serikat di sini. Nah, keterlibatan apa yang dimaksud?
Chairman Pesta Blogger 08, Wicaksono—yang dalam jagat blogger dikenal sebagai Ndoro Kakung—sebagaimana ditulis blogger Aris Heru Utomo di Kompasiana, mengaku sudah dapat mengira bahwa berperannya AS dalam mensponsori pesta blogger kali ini akan menimbulkan purbasangka dan curiga. Alasannya, ada sentimen dan prasangka tertentu dari sebagian kalangan terhadap AS.
Bagi Duta Besar AS untuk Indonesia Cameron R Hume, meraih blog berarti melaksanakan diplomasi publik di tingkat akar rumput. Tidak sekadar menakar ke mana arah kebijakan pemerintah masing-masing (G to G), tetapi juga bisa meraba perasaan warga masyarakat Indonesia melalui blog, melalui apa yang disebut Aris sebagai diplomasi publik. Selain itu, adalah tugasnya selaku diplomat untuk selalu memperkenalkan dan memelihara pemahaman tentang negerinya di masyarakat di mana dia bertugas.
Untuk itu dapat dipahami mengapa Kedubes AS di Indonesia berkenan menjadi sponsor Pesta Blogger 2008 yang mengusung tema blogging for society. Dengan cara ini, demokrasi dan semangat kebebasan berbicara yang selalu didengungkan AS ke pelosok dunia menjadi bukti nyata, tidak asal omong. Bagi Hume, kegiatan blog atau blogging merupakan bentuk dari kebebasan bicara yang individualistis sekaligus egaliter.
Kruger dan Obama
Di belahan dunia lain, blog sejatinya digunakan sebagai media alternatif untuk menyampaikan berita yang ”tidak seksi” alias tidak cukup menarik bagi media arus utama. Masalah kesehatan penduduk lokal, masalah ketimpangan pendidikan, ketidakadilan dalam kesempatan memperoleh pekerjaan, hanyalah contoh kecil saja di mana blog bisa berperan di dalamnya. Blog bisa menyampaikan semua ”ketidakadilan” itu tanpa dibatasi ruang dan waktu.
Pada tahun 2008 ini blog naik daun seiring dengan terpilihnya Barack Obama sebagai Presiden AS. Obama, seperti telah banyak ditulis, memiliki blog sendiri dan menjadi bagian dari belasan situs pertemanan seperti Facebook. Padahal, Justin Hall, pemuda kelahiran 16 Desember 1974 yang juga seorang wartawan paruh waktu, tidak berpikir sejauh itu saat menjadi blogger pertama yang menulis catatan hariannya di internet tahun 1994.
Masih segar dalam ingatan, bagaimana pemenang Nobel bidang Ekonomi, Paul Krugman, demikian lugas menuangkan gagasannya yang jauh lebih segar dibanding dengan apa yang ditulisnya di The New York Times versi print saat ia menulis di blog miliknya. Di http://krugan.blogs.nytimes.com yang juga menjadi bagian koran ternama itu, Krugman menulis persoalan berat menjadi ringan dan enak dibaca. Alhasil, Krugman lebih dikenal sebagai blogger ketimbang sebagai kolumnis atau analis ekonomi.
Usia blog belumlah terlalu lama. Kalau menyebut Hall sebagai orang pertama yang ngeblog, usianya baru 14 tahun. Namun, di usinya yang tergolong muda, blog telah dimanfaatkan berbagai golongan masyarakat dengan berbagai tingkatan usia.
Jangan heran kalau Uskup Bandung yang sudah tergolong usia senja, Pujasumarta, memiliki blog sebagai media untuk memberitakan kegiatannya sekaligus menyapa jemaatnya. Ada juga Marsekal Muda (Purn) Prayitno Ramelan yang mengisi masa-masa pensiunnya dengan ngeblog. Violis Maylafflayza sudah sejak lama memanfaatkan blog dan situs pertemanannya sebagai media komunikasi untuk menyapa penggemarnya.
Anda belum ngeblog? Jangan dengar ledekan Jenderal Naga Bonar ”Apa kata dunia?” Mulai sajalah ngeblog saat ini juga!
Sumber: KOMPAS Kamis, 20 November 2008 | 01:19 WIB
Upaya Menjadi Lebih Dipercaya
Oleh PEPIH NUGRAHA
Sederhana saja mengukur penerimaan masyarakat atas blog di negeri ini. Tahun lalu, pada Pesta Blogger 2007, jumlah peserta hanya 500 orang. Kini, ketika Pesta Blogger 2008 kembali digelar, jumlah peserta yang terdaftar mencapai 1.200 orang. Jika tidak dibatasi, jumlahnya bisa jadi di atas 2.000 orang.
Memang parameter yang digunakan terlalu sederhana. Bukan maksud mengukur apakah blog diterima atau tidak oleh masyarakat, sebab hal itu tidak terlalu bermanfaat untuk dibahas. Lebih baik mengetahui bagaimana masyarakat memanfaatkan blog itu untuk berbagai keperluan, tidak sekadar bergaya atau asal punya blog. Maklum, sejak kelahirannya sampai kini blog masih dicibir banyak orang.
Padahal, dalam perkembangannya, blog ada yang mewujud sebagai citizen journalism, media indie yang menjadi bacaan alternatif. Dengan citizen journalism, siapa pun bisa memanfaatkan blog sebagai media penyampai pesan. Adagium ”media (blog) adalah pesan itu sendiri” menjadi terbukti di sini. Dan Gilmor dengan bukunya, We Media, mengklaim bahwa setiap orang adalah wartawan.
Kegiatan melaporkan suatu peristiwa dan menuliskannya pada media untuk disebarluaskan kepada khalayak bukan lagi milik jurnalis media arus utama. Warga bisa menjadi wartawan! Namun, tentu saja Gilmor mengatakan hal itu setelah tumbuh dan berkembangnya media online, web, dan kini blog yang bisa diperoleh secara mudah. Namun, karena mudahnya, blog didapat, ada anggapan bahwa ia tidak harus dipelihara dengan baik.
Dianggap tidak kredibel karena ulah segelintir blogger yang memanfaatkan blog untuk kepentingan sensasi belaka. Contoh ketika blog menjadi kontroversi dan dianggap sebagai penyebar fitnah setelah beredarnya rumor bahwa calon wakil presiden AS dari Partai Republik, Sarah Palin, tidak tahu Afrika merupakan benua. Rumor murahan ini ternyata berasal dari blog seseorang yang mengaku bernama Martin Eisenstadt.
Sayangnya, isu ini lalu ditangkap mentah-mentah media arus utama dan disiarkan tanpa berupaya melakukan cek dan ricek, meski pada akhirnya diralat.
Keterlibatan Amerika Serikat
Kalau begitu, apa yang harus dilakukan seorang blogger agar setiap posting-annya dapat dipercaya. ”Think before posting”, demikian pesan yang seharusnya ditangkap oleh setiap blogger sebelum menaruh tulisan dan gagasannya di blog. Apa yang di-posting-kan di blog harus menjadi tanggung jawab masing-masing blogger.
Wartawan senior harian ini, Ninok Leksono, pernah menulis di blog Kompasiana yang beralamat di http://kompasiana.com mengenai bagaimana seharusnya blog menjalankan fungsinya. Menurut dia, setiap pemilik blog berkepentingan agar blog miliknya tetap kredibel dan dipercaya warga pembaca lainnya. Bahkan, untuk Indonesia, katanya, ”Kredibilitas masih perlu ditambah dengan kearifan.”
Kembali ke Pesta Blogger 08 yang kali kedua ini digelar di Auditorium Gedung BPPT II Jakarta, Sabtu (22/11), ini menjadi sebuah pesta yang layak disimak. Bukan karena berkumpulnya komunitas blogger secara masif di sana, tetapi karena keterlibatan Pemerintah Amerika Serikat di sini. Nah, keterlibatan apa yang dimaksud?
Chairman Pesta Blogger 08, Wicaksono—yang dalam jagat blogger dikenal sebagai Ndoro Kakung—sebagaimana ditulis blogger Aris Heru Utomo di Kompasiana, mengaku sudah dapat mengira bahwa berperannya AS dalam mensponsori pesta blogger kali ini akan menimbulkan purbasangka dan curiga. Alasannya, ada sentimen dan prasangka tertentu dari sebagian kalangan terhadap AS.
Bagi Duta Besar AS untuk Indonesia Cameron R Hume, meraih blog berarti melaksanakan diplomasi publik di tingkat akar rumput. Tidak sekadar menakar ke mana arah kebijakan pemerintah masing-masing (G to G), tetapi juga bisa meraba perasaan warga masyarakat Indonesia melalui blog, melalui apa yang disebut Aris sebagai diplomasi publik. Selain itu, adalah tugasnya selaku diplomat untuk selalu memperkenalkan dan memelihara pemahaman tentang negerinya di masyarakat di mana dia bertugas.
Untuk itu dapat dipahami mengapa Kedubes AS di Indonesia berkenan menjadi sponsor Pesta Blogger 2008 yang mengusung tema blogging for society. Dengan cara ini, demokrasi dan semangat kebebasan berbicara yang selalu didengungkan AS ke pelosok dunia menjadi bukti nyata, tidak asal omong. Bagi Hume, kegiatan blog atau blogging merupakan bentuk dari kebebasan bicara yang individualistis sekaligus egaliter.
Kruger dan Obama
Di belahan dunia lain, blog sejatinya digunakan sebagai media alternatif untuk menyampaikan berita yang ”tidak seksi” alias tidak cukup menarik bagi media arus utama. Masalah kesehatan penduduk lokal, masalah ketimpangan pendidikan, ketidakadilan dalam kesempatan memperoleh pekerjaan, hanyalah contoh kecil saja di mana blog bisa berperan di dalamnya. Blog bisa menyampaikan semua ”ketidakadilan” itu tanpa dibatasi ruang dan waktu.
Pada tahun 2008 ini blog naik daun seiring dengan terpilihnya Barack Obama sebagai Presiden AS. Obama, seperti telah banyak ditulis, memiliki blog sendiri dan menjadi bagian dari belasan situs pertemanan seperti Facebook. Padahal, Justin Hall, pemuda kelahiran 16 Desember 1974 yang juga seorang wartawan paruh waktu, tidak berpikir sejauh itu saat menjadi blogger pertama yang menulis catatan hariannya di internet tahun 1994.
Masih segar dalam ingatan, bagaimana pemenang Nobel bidang Ekonomi, Paul Krugman, demikian lugas menuangkan gagasannya yang jauh lebih segar dibanding dengan apa yang ditulisnya di The New York Times versi print saat ia menulis di blog miliknya. Di http://krugan.blogs.nytimes.com yang juga menjadi bagian koran ternama itu, Krugman menulis persoalan berat menjadi ringan dan enak dibaca. Alhasil, Krugman lebih dikenal sebagai blogger ketimbang sebagai kolumnis atau analis ekonomi.
Usia blog belumlah terlalu lama. Kalau menyebut Hall sebagai orang pertama yang ngeblog, usianya baru 14 tahun. Namun, di usinya yang tergolong muda, blog telah dimanfaatkan berbagai golongan masyarakat dengan berbagai tingkatan usia.
Jangan heran kalau Uskup Bandung yang sudah tergolong usia senja, Pujasumarta, memiliki blog sebagai media untuk memberitakan kegiatannya sekaligus menyapa jemaatnya. Ada juga Marsekal Muda (Purn) Prayitno Ramelan yang mengisi masa-masa pensiunnya dengan ngeblog. Violis Maylafflayza sudah sejak lama memanfaatkan blog dan situs pertemanannya sebagai media komunikasi untuk menyapa penggemarnya.
Anda belum ngeblog? Jangan dengar ledekan Jenderal Naga Bonar ”Apa kata dunia?” Mulai sajalah ngeblog saat ini juga!
Sumber: KOMPAS Kamis, 20 November 2008 | 01:19 WIB
Minggu, 16 November 2008
Ejacs: a JavaScript interpreter for Emacs
So! I have all these cool things I want to write about, but I broke my thumbnail. Can you tell that's a long story?
See, this summer I got excited about playing guitar again. I usually switch between all-guitar and all-piano every other year or so. This summer I dusted off the guitars and learned a bunch of pieces, and even composed one. I was prepping for — among other things — a multimedia blog entry. It was going to have a YouTube video, and a detailed discussion of a wacky yet powerful music programming language you've probably heard of but never used, and generally just be really cool.
And then it all came crashing down when I busted my thumbnail off. And I mean off — it broke off at least a quarter inch below where the nail and skin meet. Ick. I just accidentally jabbed my steering wheel, and that was that.
I remember reading an interview with some dude who said he had punched a shark in the nose. He said it was like punching a steering wheel. So now I know more or less what it's like to punch a shark in the nose, I guess. There's always an upside!
Anyway, that was going to be my magnum opus (literally: Op. 1) for the year, but it fell through for now. I'll have to revisit the idea next year. My thumbnail's back, but it's been at least 2 months since I touched my guitar, so I'll have to start over again.
Work has been extraordinarily busy, what with having to collect all these Nuka-Cola Quantum bottles and so on. I'm sure you can imagine. So I haven't had much time to blog lately.
But I do like to publish at least once a month, whether or not anyone actually cares. It's been about a month, or it feels that way anyway, and all I have to show for it is this box of Blamco Mac and Cheese.
So I'm cheating this month.
You know how on Halloween how you walk around in your costume holding your little bag and you say "trick or treat", and every once in a while some asshole does a trick instead of dumping half a pound of candy into your bag? And then he has to explain to all the dumbfounded and unhappy kids that "Trick or Treat" means that a trick is perfectly legal according to the semantics of logical-OR, and the kids remember that a-hole for the rest of their childhoods and avoid his house next year?
Yeah.
So I'm doing a trick this time. Hee. It's actually kind of fun when you're on the giving end.
My trick is this: in lieu of saying anything meaningful or contemporarily relevant, I'm writing about something I did over a year ago. And there isn't much to say, so this really will be short.
Ejacs
Around a year ago, I wrote a blog called Stevey's Boring Status Update, mostly in response to wild rumors that I'd been fired from Google. Not so. Not yet, anyway.
In that blog I mentioned I was working nights part-time (among other things) on a JavaScript interpreter for Emacs, written entirely in Emacs Lisp. I also said I didn't have a name for it. A commenter named Andrew Barry suggested that I should not call it Ejacs, and the name stuck.
Ejacs is a port of Narcissus. Narcissus is a JavaScript interpreter written in JavaScript, by Brendan Eich, who by pure unexpected coincidence is also the inventor of JavaScript. Narcissus is fairly small, so I thought it would be fun to port it to Emacs Lisp.
It turns out Narcissus is fundamentally incomplete. It cheats. It's that trick guy on Halloween. Narcissus has a working parser and evaluator, but for its runtime it calls JavaScript. So it's kind of like saying you're building a car by starting from scratch, using absolutely nothing except for a working car.
This meant I wound up having to write my own Ecma-262 runtime, so that the evaluator would have something to chew on. In particular, the Ecma-262 runtime consists of all the built-in properties, functions and objects: Object, Function, Array, String, Math, Date, RegExp, Boolean, Infinity, NaN, parseInt, encodeURIComponent, etc. A whole bunch of stuff.
I basically did this by reading the ECMA-262 specification and translating their algorithms into Emacs-Lisp. That spec is lousy for learning JavaScript, but it's absolutely indispensable if you're trying to implement JavaScript.
I didn't know Emacs-Lisp all that well before I started, but boy howdy, I know it now.
Emacs actually has a pretty huge runtime of its own — bigger than you would ever, ever expect given its mundane title of "text editor". Emacs has arbitrary-precision mathematics, deep Unicode support, rich Date and Calendar support, and an extensive, fairly complete operating system interface. So a lot of the porting time was just digging through Emacs documentation (also extensive) looking for the Emacs version of whatever it was I was porting. That was nice.
I had big plans for Ejacs. I was going to make it a full-featured, high-performance JavaScript interpreter, with all the Emacs internals surfaced as JavaScript native host objects, so you could write Emacs customizations using object-oriented programming. It was totally going to be the "meow" part of the cat.
And then I broke my thumbnail.
Actually, what happened was js2-mode.
js2-mode
After I got the interpreter working, I was at this crossroads. There were two big use cases: a JavaScript editing mode, or a JavaScript Emacs development mode. Both were going to be a lot of work.
It turns out you really want the editing mode first, if possible, so that when you're doing all your JavaScript programming you have a decent environment for it. So I picked the editing mode.
Unfortunately I found the Ejacs parser wasn't full-featured enough for my editing needs, since at the time I was working on my Rhino-based Rails clone and writing tons of JavaScript 1.7 code on the JVM.
I spent a little time trying to beef up the parser, then realized it would be a lot faster to just rewrite it by porting Mozilla Rhino's parser, which is (only) about 2500 lines of Java code. Ejacs is something like 12,000 lines of Emacs-Lisp code, all told, so that didn't seem like a big deal.
So I jumped in, only to find that while the parser is 2500 lines of code, the scanner is another 2000 lines of code, and there's another 500 or so lines of support code in other files. So I was really looking at porting 5000 lines of Java code.
Moreover, the parse tree Rhino builds is basically completely incompatible with the Ejacs parse tree. It was richer and more complex, and needed more complicated structures to represent it.
So after I'd ported the Rhino parse tree, what I really had was a different code base. I went ahead and finished up the editing mode, or at least enough to make it barely workable (another 5000 lines of code), and launched it. It was a surprisingly big effort.
And it left poor Ejacs lying unused in the basement.
So today, faced with nothing to write about, I figured I'd dust off Ejacs, launch it with lots of fanfare, and then you'd hardly notice that I cheated you. Right?
You're not coming to my house next year. I can tell already.
Anyway, here's the code: http://code.google.com/p/ejacs/
There's a README and a Wiki and installation instructions and stuff. I can't remember how to put the code in SVN, and I'm having trouble finding it on the code.google.com site. As soon as I figure it out I'll also make it available via SVN.
Emacs Lisp vs. JavaScript
In the interests of having something resembling original worthwhile content today, I'll do a little comparison of Emacs Lisp and JavaScript. I know a lot about both languages now, and a few folks mentioned that a comparison would be potentially interesting.
Especially since I think JavaScript is a better language.
So... the best way to compare programming languages is by analogy to cars. Lisp is a whole family of languages, and can be broken down approximately as follows:
This succinct yet completely accurate synopsis shows that all Lisps have their attractions, and yet each also has a niche. You can choose a Lisp for the busy person, a Lisp for someone without much time, or a Lisp for the dedicated hobbyist, and you'll find that no matter which one you choose, it's missing the library you need.
Emacs Lisp can get the job done. No question. It's a car, and it moves. It's better than walking. But it pretty much combines the elegance of Common Lisp with the industrial strength of Scheme, without hitting either of them, if you catch my drift.
Anyway, here's the comparison. Here's why I think JavaScript is a better language than Emacs Lisp.
Problem #1: Momentum
A recurring theme is that Elisp and JavaScript both will both exhibit a particular problem, and there are specific near-term plans to fix it in JavaScript, but no long-term plans to fix it in Elisp.
It's easier to resign yourself to a workaround when you know it's temporary. If you know the language is going to be enhanced, you can even design your code to accommodate the enhancements more easily when they appear.
People are working on improving JavaScript. It's not happening quite as fast as I'd hoped earlier this year, but it's still happening. As far as I know, Emacs Lisp is "finished" in the sense that no further evolution to the language is deemed necessary by the Emacs development team.
Problem #2: No encapsulation
Every symbol in Emacs-Lisp is in the global namespace. There is rudimentary support for hand-rolled namespaces using obarrays, but there's no equivalent to Common Lisp's
The only effective workaround for this problem is to prefix every symbol with the package name. This practice has become so entrenched in Emacs-Lisp programming that many packages (e.g.
The main adverse consequence of this problem in practice is program verbosity; it makes Emacs-Lisp more difficult to read and write than Common Lisp or Scheme. It can also have a non-negligible impact on performance, especially of interpreted code, as the prefix characters can approach 5% to 10% of total program size in some cases.
The problems run slightly deeper than simple verbosity. Without namespaces you have no real encapsulation facility: there is no convenient way to make a "package-private" variable or function. In practice there's little problem with program integrity; it's hard for an external package to change a "private" variable inadvertently in the presence of symbol prefixes. However, it makes it annoyingly difficult for users of the package to discern the "important" top-level configuration variables and program entry points from the unimportant ones. Elisp attempts a few conventions here, but it's a far cry from real encapsulation support.
JavaScript also lacks namespaces. They're being added in ES/Harmony, but in the meantime, browser JavaScript code typically uses the same name-prefixing practice as Emacs-Lisp.
However, JavaScript has lexical closures, which provide a mechanism for creating private names. One common encapsulation idiom in browser JavaScript is to wrap a code unit in an anonymous lambda, so that all the functions in the code unit become nested functions that close lexically over the top-level names in the anonymous lambda. This trick is nowhere near as effective in Emacs-Lisp, for several reasons:
Some elisp code (e.g. much of the code in cc-engine) prefers to work around the namespace problem by using enormous functions that can be thousands of lines long, since let-bound variables are slightly better encapsulated. Even this is broken by elisp's dynamic scope:
So let-bound variables in elisp can still be destroyed by your callee: a dangerous situation at best.
Emacs is basically one big program soup. There's almost no encapsulation to speak of, and it hurts.
Problem #3: No delegation
One of the big advantages to object-oriented programming is that there is both syntactic support and runtime support for automatic delegation to a "supertype". You can specialize a type and delegate some of the functionality to the base type. Call it virtual methods or prototype inheritance or whatever you like; most successful languages support some notion of automatic delegation.
Emacs Lisp is a lot like ANSI C: it gives you arrays, structs and functions. You don't get pointers, but you do get garbage collection and good support for linked lists, so it's roughly a wash.
For any sufficiently large program, you need delegation. In Ejacs I wound up having to implement my own virtual method tables, because JavaScript objects inherit from
Writing your own virtual method dispatch is just not something you should have to do in 2008.
Problem #4: Properties
I wrote about this at length in a recent blog post, The Universal Design Pattern. JavaScript is fundamentally a properties-based language, and it's really nice to be able to just slap named properties on things when you need a place to store data.
Emacs Lisp only offers properties in the form of simple plists – linked lists where the odd entries are names and the even entries are values. Symbols have plists, and symbols operate a little bit like very lightweight Java classes (in that they're in the global namespace), but that only gets you so far. If you want the full JavaScript implementation of the Properties Pattern, you'll have to write a lot of code.
And so I did. Your implementation choice for object property lists has a huge impact on runtime performance. Emacs has hashtables, but they're heavyweight: if you try to instantiate thousands of them it slows Emacs to a crawl. So they're no good for the default
I wound up writing a hybrid model, where the storage starts with lightweight alists, and as you add properties to an object instance, it crosses a threshold (I set it to 50, which seemed to be about right from profiling), it copies the properties into a hashtable. This had a dramatic increase in performance, but it was a lot of work.
I experimented with using a splay tree. I implemented Sleater and Tarjan's splay tree algorithm in elisp; Ejacs comes with a standalone
And then in the end, after I was done with my implementation, it was a library (at least from the Emacs-Lisp side of the house). It wasn't an object system for Lisp. It's only really usable inside the JavaScript interpreter, where it has syntactic support.
You really want syntactic support. Sure, people have ported subsets of CLOS to Emacs Lisp, but I've always found them a bit clunky. And even in CLOS it's hard to implement the Properties Pattern. You don't get it by default. CLOS has lots of support for compile-time slots and virtual dispatch, but very little support for dynamic properties. It's not terribly hard to build in, but that's my point: for something that fundamental, you don't want to have to build it.
Problem #5: No polymorphic
One of the great strengths of JavaScript is the
This is even true for functions! A function in JavaScript can print its own source code. This is an amazingly powerful feature.
In Emacs Lisp, some objects have first-class print representations. Lists and vectors do, for instance:
But in Emacs Lisp, many built-in types (notably hashtables and functions) do NOT have a way to serialize back as source code. This is a serious omission.
Also, trying to print a sufficiently large tree made entirely of
The problem of polymorphic debug-printing (or text-serialization) is, I think, a byproduct of Emacs not being object-oriented. If you want a debug dump of a data structure, you write a function to do it. But Emacs provides a half-assed solution: it debug-prints lists very nicely, even detecting cycles and using the #-syntax for representing graph structures (as does SpiderMonkey/JavaScript). But it has no useful debugging representation for hashtables, functions, buffers or other built-in structures, and there's no way to install your own custom printer so that the debugger and other subsystems will use it.
So it sucks. Printing data structures in Emacs just sucks.
The situation in Ecma-262-compliant JavaScript really isn't that much better, although you can at least install your own
And all else being equal, at least JavaScript functions print themselves.
Emacs advantages: Macros and S-expressions
Pound for pound, Emacs Lisp seems roughly as expressive as JavaScript or Java for writing everyday code. It shouldn't be that way. Emacs Lisp ought to be more succinct because it's Lisp, but it's incredibly verbose because of the namespace problem, and it's also verbose to the extent that you want to use the properties pattern without worrying about alist or hashtable performance.
Elisp does have a few places where it shines, though. One of them is the
Some programmers are still operating under the (ancient? legacy?) assumption that the
The
Emacs Lisp has
Elisp is s-expression based, which is a mixed bag. It has some advantages, no question. However, it fares poorly in two very common domains: object property access, and algebraic expressions.
JavaScript is NOT s-expression based (or it wouldn't be a successful language, many would argue), but it does offer some of the benefits of s-expressions. JSON is one such benefit. JavaScript's declarative object literals (or as a Lisp person would say, "syntax for hashes") and arrays provide a powerful mechanism for designing and walking your own declarative data structures.
JavaScript also has all the usual (which is to say, expected) support for algebraic operators. And unlike Java, JavaScript even got the precedence right, so it's not full of redundant parentheses.
Overall Comparison
In the end, it comes down to personal choice. I've now written at least 30,000 lines of serious code in both Emacs Lisp and JavaScript, which pales next to the 750,000 or so lines of Java I've crapped out, and doesn't even compare to the amount of C, Python, assembly language or other stuff I've written.
But 30,000 lines is a pretty good hunk of code for getting to know a language. Especially if you're writing an interpreter for one language in another language: you wind up knowing both better than you ever wanted to know them.
And I prefer JavaScript over Emacs Lisp.
That said, I suspect I would probably prefer Clojure over Rhino, if I ever get a chance to sit down with the durn thing and use it, so it's not so much "JavaScript vs. Lisp" as it is vs. Emacs Lisp.
I would love to see Emacs Lisp get reader macros, closures, some namespace support, and the ability to install your own print functions. This reasonably small set of features would be a huge step in usability.
However, for the nonce I'm focusing on JavaScript. I've found that JavaScript is a language that smart people like. It's weird, but I keep meeting really really smart people, folks who (unlike me) are actually intelligent, and they like JavaScript. They're always a little defensive about it, and almost a little embarrassed to admit it. But they think of it as an elegant, powerful, slightly flawed but quite enjoyable little language.
I tell ya: if you're a programming language, it's a very good thing to have smart people liking you.
It doesn't make me smart, but I kinda like it too. Even though there's (still) a lot of hype these days about Java, and people tootling on about how Java's going to be the next big Web language... I just don't see it happening. There are too many smart people out there who like JavaScript.
So enjoy the interpreter. Ejacs is just a toy, but I think it also shows a kind of promise. Scripting Emacs using JavaScript (if anyone ever actually implements it) could be really interesting. It could open up the world's most powerful, advanced editing environment to millions of people. Neat.
In the meantime, it doesn't actually do squat except interpret EcmaScript in a little isolated console, so don't get your hopes up.
Reminder — here's the Ejacs URL: http://code.google.com/p/ejacs - enjoy!
And with that, I'm off to find some Nuka-Cola Quantum. I just wish those bastards hadn't capped me at level 20.
See, this summer I got excited about playing guitar again. I usually switch between all-guitar and all-piano every other year or so. This summer I dusted off the guitars and learned a bunch of pieces, and even composed one. I was prepping for — among other things — a multimedia blog entry. It was going to have a YouTube video, and a detailed discussion of a wacky yet powerful music programming language you've probably heard of but never used, and generally just be really cool.
And then it all came crashing down when I busted my thumbnail off. And I mean off — it broke off at least a quarter inch below where the nail and skin meet. Ick. I just accidentally jabbed my steering wheel, and that was that.
I remember reading an interview with some dude who said he had punched a shark in the nose. He said it was like punching a steering wheel. So now I know more or less what it's like to punch a shark in the nose, I guess. There's always an upside!
Anyway, that was going to be my magnum opus (literally: Op. 1) for the year, but it fell through for now. I'll have to revisit the idea next year. My thumbnail's back, but it's been at least 2 months since I touched my guitar, so I'll have to start over again.
Work has been extraordinarily busy, what with having to collect all these Nuka-Cola Quantum bottles and so on. I'm sure you can imagine. So I haven't had much time to blog lately.
But I do like to publish at least once a month, whether or not anyone actually cares. It's been about a month, or it feels that way anyway, and all I have to show for it is this box of Blamco Mac and Cheese.
So I'm cheating this month.
You know how on Halloween how you walk around in your costume holding your little bag and you say "trick or treat", and every once in a while some asshole does a trick instead of dumping half a pound of candy into your bag? And then he has to explain to all the dumbfounded and unhappy kids that "Trick or Treat" means that a trick is perfectly legal according to the semantics of logical-OR, and the kids remember that a-hole for the rest of their childhoods and avoid his house next year?
Yeah.
So I'm doing a trick this time. Hee. It's actually kind of fun when you're on the giving end.
My trick is this: in lieu of saying anything meaningful or contemporarily relevant, I'm writing about something I did over a year ago. And there isn't much to say, so this really will be short.
Ejacs
Around a year ago, I wrote a blog called Stevey's Boring Status Update, mostly in response to wild rumors that I'd been fired from Google. Not so. Not yet, anyway.
In that blog I mentioned I was working nights part-time (among other things) on a JavaScript interpreter for Emacs, written entirely in Emacs Lisp. I also said I didn't have a name for it. A commenter named Andrew Barry suggested that I should not call it Ejacs, and the name stuck.
Ejacs is a port of Narcissus. Narcissus is a JavaScript interpreter written in JavaScript, by Brendan Eich, who by pure unexpected coincidence is also the inventor of JavaScript. Narcissus is fairly small, so I thought it would be fun to port it to Emacs Lisp.
It turns out Narcissus is fundamentally incomplete. It cheats. It's that trick guy on Halloween. Narcissus has a working parser and evaluator, but for its runtime it calls JavaScript. So it's kind of like saying you're building a car by starting from scratch, using absolutely nothing except for a working car.
This meant I wound up having to write my own Ecma-262 runtime, so that the evaluator would have something to chew on. In particular, the Ecma-262 runtime consists of all the built-in properties, functions and objects: Object, Function, Array, String, Math, Date, RegExp, Boolean, Infinity, NaN, parseInt, encodeURIComponent, etc. A whole bunch of stuff.
I basically did this by reading the ECMA-262 specification and translating their algorithms into Emacs-Lisp. That spec is lousy for learning JavaScript, but it's absolutely indispensable if you're trying to implement JavaScript.
I didn't know Emacs-Lisp all that well before I started, but boy howdy, I know it now.
Emacs actually has a pretty huge runtime of its own — bigger than you would ever, ever expect given its mundane title of "text editor". Emacs has arbitrary-precision mathematics, deep Unicode support, rich Date and Calendar support, and an extensive, fairly complete operating system interface. So a lot of the porting time was just digging through Emacs documentation (also extensive) looking for the Emacs version of whatever it was I was porting. That was nice.
I had big plans for Ejacs. I was going to make it a full-featured, high-performance JavaScript interpreter, with all the Emacs internals surfaced as JavaScript native host objects, so you could write Emacs customizations using object-oriented programming. It was totally going to be the "meow" part of the cat.
And then I broke my thumbnail.
Actually, what happened was js2-mode.
js2-mode
After I got the interpreter working, I was at this crossroads. There were two big use cases: a JavaScript editing mode, or a JavaScript Emacs development mode. Both were going to be a lot of work.
It turns out you really want the editing mode first, if possible, so that when you're doing all your JavaScript programming you have a decent environment for it. So I picked the editing mode.
Unfortunately I found the Ejacs parser wasn't full-featured enough for my editing needs, since at the time I was working on my Rhino-based Rails clone and writing tons of JavaScript 1.7 code on the JVM.
I spent a little time trying to beef up the parser, then realized it would be a lot faster to just rewrite it by porting Mozilla Rhino's parser, which is (only) about 2500 lines of Java code. Ejacs is something like 12,000 lines of Emacs-Lisp code, all told, so that didn't seem like a big deal.
So I jumped in, only to find that while the parser is 2500 lines of code, the scanner is another 2000 lines of code, and there's another 500 or so lines of support code in other files. So I was really looking at porting 5000 lines of Java code.
Moreover, the parse tree Rhino builds is basically completely incompatible with the Ejacs parse tree. It was richer and more complex, and needed more complicated structures to represent it.
So after I'd ported the Rhino parse tree, what I really had was a different code base. I went ahead and finished up the editing mode, or at least enough to make it barely workable (another 5000 lines of code), and launched it. It was a surprisingly big effort.
And it left poor Ejacs lying unused in the basement.
So today, faced with nothing to write about, I figured I'd dust off Ejacs, launch it with lots of fanfare, and then you'd hardly notice that I cheated you. Right?
You're not coming to my house next year. I can tell already.
Anyway, here's the code: http://code.google.com/p/ejacs/
There's a README and a Wiki and installation instructions and stuff. I can't remember how to put the code in SVN, and I'm having trouble finding it on the code.google.com site. As soon as I figure it out I'll also make it available via SVN.
Emacs Lisp vs. JavaScript
In the interests of having something resembling original worthwhile content today, I'll do a little comparison of Emacs Lisp and JavaScript. I know a lot about both languages now, and a few folks mentioned that a comparison would be potentially interesting.
Especially since I think JavaScript is a better language.
So... the best way to compare programming languages is by analogy to cars. Lisp is a whole family of languages, and can be broken down approximately as follows:
- Scheme is an exotic sports car. Fast. Manual transmission. No radio.
- Emacs Lisp is a 1984 Subaru GL 4WD: "the car that's always in front of you."
- Common Lisp is Howl's Moving Castle.
This succinct yet completely accurate synopsis shows that all Lisps have their attractions, and yet each also has a niche. You can choose a Lisp for the busy person, a Lisp for someone without much time, or a Lisp for the dedicated hobbyist, and you'll find that no matter which one you choose, it's missing the library you need.
Emacs Lisp can get the job done. No question. It's a car, and it moves. It's better than walking. But it pretty much combines the elegance of Common Lisp with the industrial strength of Scheme, without hitting either of them, if you catch my drift.
Anyway, here's the comparison. Here's why I think JavaScript is a better language than Emacs Lisp.
Problem #1: Momentum
A recurring theme is that Elisp and JavaScript both will both exhibit a particular problem, and there are specific near-term plans to fix it in JavaScript, but no long-term plans to fix it in Elisp.
It's easier to resign yourself to a workaround when you know it's temporary. If you know the language is going to be enhanced, you can even design your code to accommodate the enhancements more easily when they appear.
People are working on improving JavaScript. It's not happening quite as fast as I'd hoped earlier this year, but it's still happening. As far as I know, Emacs Lisp is "finished" in the sense that no further evolution to the language is deemed necessary by the Emacs development team.
Problem #2: No encapsulation
Every symbol in Emacs-Lisp is in the global namespace. There is rudimentary support for hand-rolled namespaces using obarrays, but there's no equivalent to Common Lisp's
in-package, making obarrays effectively useless as a tool for code isolation.The only effective workaround for this problem is to prefix every symbol with the package name. This practice has become so entrenched in Emacs-Lisp programming that many packages (e.g.
apropos and the elp elisp profiler) rely on the convention for proper operation.The main adverse consequence of this problem in practice is program verbosity; it makes Emacs-Lisp more difficult to read and write than Common Lisp or Scheme. It can also have a non-negligible impact on performance, especially of interpreted code, as the prefix characters can approach 5% to 10% of total program size in some cases.
The problems run slightly deeper than simple verbosity. Without namespaces you have no real encapsulation facility: there is no convenient way to make a "package-private" variable or function. In practice there's little problem with program integrity; it's hard for an external package to change a "private" variable inadvertently in the presence of symbol prefixes. However, it makes it annoyingly difficult for users of the package to discern the "important" top-level configuration variables and program entry points from the unimportant ones. Elisp attempts a few conventions here, but it's a far cry from real encapsulation support.
JavaScript also lacks namespaces. They're being added in ES/Harmony, but in the meantime, browser JavaScript code typically uses the same name-prefixing practice as Emacs-Lisp.
However, JavaScript has lexical closures, which provide a mechanism for creating private names. One common encapsulation idiom in browser JavaScript is to wrap a code unit in an anonymous lambda, so that all the functions in the code unit become nested functions that close lexically over the top-level names in the anonymous lambda. This trick is nowhere near as effective in Emacs-Lisp, for several reasons:
- elisp is not lexically scoped and has no closures
- elisp nested defuns are still entered into the global namespace
- CL's
`flet'and `labels' are only weakly supported, via macros, and they frequently confuse the debugger, indenter, and other tools.
Some elisp code (e.g. much of the code in cc-engine) prefers to work around the namespace problem by using enormous functions that can be thousands of lines long, since let-bound variables are slightly better encapsulated. Even this is broken by elisp's dynamic scope:
(defun foo ()
(setq x 7))
(defun bar ()
(let ((x 6))
(foo)
x)) ; you would expect x to still be 6 here
(bar)
7 ; d'oh!
So let-bound variables in elisp can still be destroyed by your callee: a dangerous situation at best.
Emacs is basically one big program soup. There's almost no encapsulation to speak of, and it hurts.
Problem #3: No delegation
One of the big advantages to object-oriented programming is that there is both syntactic support and runtime support for automatic delegation to a "supertype". You can specialize a type and delegate some of the functionality to the base type. Call it virtual methods or prototype inheritance or whatever you like; most successful languages support some notion of automatic delegation.
Emacs Lisp is a lot like ANSI C: it gives you arrays, structs and functions. You don't get pointers, but you do get garbage collection and good support for linked lists, so it's roughly a wash.
For any sufficiently large program, you need delegation. In Ejacs I wound up having to implement my own virtual method tables, because JavaScript objects inherit from
Object (and in some cases, Function, which inherits from Object).Writing your own virtual method dispatch is just not something you should have to do in 2008.
Problem #4: Properties
I wrote about this at length in a recent blog post, The Universal Design Pattern. JavaScript is fundamentally a properties-based language, and it's really nice to be able to just slap named properties on things when you need a place to store data.
Emacs Lisp only offers properties in the form of simple plists – linked lists where the odd entries are names and the even entries are values. Symbols have plists, and symbols operate a little bit like very lightweight Java classes (in that they're in the global namespace), but that only gets you so far. If you want the full JavaScript implementation of the Properties Pattern, you'll have to write a lot of code.
And so I did. Your implementation choice for object property lists has a huge impact on runtime performance. Emacs has hashtables, but they're heavyweight: if you try to instantiate thousands of them it slows Emacs to a crawl. So they're no good for the default
Object property list. Emacs also has associative arrays (alists), but their performance is O(n), making them no good for objects with more than maybe 30 or 40 properties.I wound up writing a hybrid model, where the storage starts with lightweight alists, and as you add properties to an object instance, it crosses a threshold (I set it to 50, which seemed to be about right from profiling), it copies the properties into a hashtable. This had a dramatic increase in performance, but it was a lot of work.
I experimented with using a splay tree. I implemented Sleater and Tarjan's splay tree algorithm in elisp; Ejacs comes with a standalone
splay-tree.el that you can use in your programs if you like. I was hoping that its LRU cache-like properties would help, but I never found a use case where it was faster than my alist/hashtable hybrid, so it's not currently used for anything.And then in the end, after I was done with my implementation, it was a library (at least from the Emacs-Lisp side of the house). It wasn't an object system for Lisp. It's only really usable inside the JavaScript interpreter, where it has syntactic support.
You really want syntactic support. Sure, people have ported subsets of CLOS to Emacs Lisp, but I've always found them a bit clunky. And even in CLOS it's hard to implement the Properties Pattern. You don't get it by default. CLOS has lots of support for compile-time slots and virtual dispatch, but very little support for dynamic properties. It's not terribly hard to build in, but that's my point: for something that fundamental, you don't want to have to build it.
Problem #5: No polymorphic
toStringOne of the great strengths of JavaScript is the
toSource extension. I don't know if they support it over in IE-land; I haven't been a tourist there in a very long time. But in real versions of JavaScript, every object can serialize itself to source, which can then be eval'ed back to construct the original object.This is even true for functions! A function in JavaScript can print its own source code. This is an amazingly powerful feature.
In Emacs Lisp, some objects have first-class print representations. Lists and vectors do, for instance:
(let ((my-list '()))
(push 1 my-list)
(push 2 my-list)
(push 3 my-list)
my-list)
(3 2 1)
(let ((v (make-vector 3 nil)))
(aset v 0 1)
(aset v 1 2)
(aset v 2 "three")
v)
[1 2 "three"]
But in Emacs Lisp, many built-in types (notably hashtables and functions) do NOT have a way to serialize back as source code. This is a serious omission.
Also, trying to print a sufficiently large tree made entirely of
defstructs will crash Emacs, which caused me a lot of grief until I migrated my parse tree to use a mixture of defstructs and lists. Note that simply typing the name of a defstruct, or passing over it ephemerally in the debugger, will cause Emacs to try to print it, and crash. Fun.The problem of polymorphic debug-printing (or text-serialization) is, I think, a byproduct of Emacs not being object-oriented. If you want a debug dump of a data structure, you write a function to do it. But Emacs provides a half-assed solution: it debug-prints lists very nicely, even detecting cycles and using the #-syntax for representing graph structures (as does SpiderMonkey/JavaScript). But it has no useful debugging representation for hashtables, functions, buffers or other built-in structures, and there's no way to install your own custom printer so that the debugger and other subsystems will use it.
So it sucks. Printing data structures in Emacs just sucks.
The situation in Ecma-262-compliant JavaScript really isn't that much better, although you can at least install your own
toString on the built-ins. But any competent "server-side" JavaScript implementation (i.e. one designed for writing real apps, rather than securely scripting browser pages) has a way to define your own non-enumerable properties, so you can usually override the default behavior for things like toString and toSource.And all else being equal, at least JavaScript functions print themselves.
Emacs advantages: Macros and S-expressions
Pound for pound, Emacs Lisp seems roughly as expressive as JavaScript or Java for writing everyday code. It shouldn't be that way. Emacs Lisp ought to be more succinct because it's Lisp, but it's incredibly verbose because of the namespace problem, and it's also verbose to the extent that you want to use the properties pattern without worrying about alist or hashtable performance.
Elisp does have a few places where it shines, though. One of them is the
cl (Common Lisp emulation) package, which provides a whole bunch of goodies that make Elisp actually usable for real work. Defstruct and the loop macro are especially noteworthy standouts.Some programmers are still operating under the (ancient? legacy?) assumption that the
cl package is somehow deprecated or distasteful or something. They're just being silly; don't listen to them. Practicality should be the ONLY consideration.The
cl package wouldn't have been possible without macros. JavaScript has no macros, so even though it has better support for lambdas, closures, and even (in some versions) continuations, there are still copy/paste compression problems you can't solve in JavaScript.Emacs Lisp has
defmacro, which makes up for a LOT of its deficiencies. However, it really only has one flavor. Ideally, at the very least, it should support reader macros. The Emacs documentation says they were left out because they felt it wasn't worth it. Who are they to make the call? It's the users who need them. Implementer convenience is a pretty lame metric for deciding whether to support a feature, especially after 20 years of people asking for it.Elisp is s-expression based, which is a mixed bag. It has some advantages, no question. However, it fares poorly in two very common domains: object property access, and algebraic expressions.
JavaScript is NOT s-expression based (or it wouldn't be a successful language, many would argue), but it does offer some of the benefits of s-expressions. JSON is one such benefit. JavaScript's declarative object literals (or as a Lisp person would say, "syntax for hashes") and arrays provide a powerful mechanism for designing and walking your own declarative data structures.
JavaScript also has all the usual (which is to say, expected) support for algebraic operators. And unlike Java, JavaScript even got the precedence right, so it's not full of redundant parentheses.
Overall Comparison
In the end, it comes down to personal choice. I've now written at least 30,000 lines of serious code in both Emacs Lisp and JavaScript, which pales next to the 750,000 or so lines of Java I've crapped out, and doesn't even compare to the amount of C, Python, assembly language or other stuff I've written.
But 30,000 lines is a pretty good hunk of code for getting to know a language. Especially if you're writing an interpreter for one language in another language: you wind up knowing both better than you ever wanted to know them.
And I prefer JavaScript over Emacs Lisp.
That said, I suspect I would probably prefer Clojure over Rhino, if I ever get a chance to sit down with the durn thing and use it, so it's not so much "JavaScript vs. Lisp" as it is vs. Emacs Lisp.
I would love to see Emacs Lisp get reader macros, closures, some namespace support, and the ability to install your own print functions. This reasonably small set of features would be a huge step in usability.
However, for the nonce I'm focusing on JavaScript. I've found that JavaScript is a language that smart people like. It's weird, but I keep meeting really really smart people, folks who (unlike me) are actually intelligent, and they like JavaScript. They're always a little defensive about it, and almost a little embarrassed to admit it. But they think of it as an elegant, powerful, slightly flawed but quite enjoyable little language.
I tell ya: if you're a programming language, it's a very good thing to have smart people liking you.
It doesn't make me smart, but I kinda like it too. Even though there's (still) a lot of hype these days about Java, and people tootling on about how Java's going to be the next big Web language... I just don't see it happening. There are too many smart people out there who like JavaScript.
So enjoy the interpreter. Ejacs is just a toy, but I think it also shows a kind of promise. Scripting Emacs using JavaScript (if anyone ever actually implements it) could be really interesting. It could open up the world's most powerful, advanced editing environment to millions of people. Neat.
In the meantime, it doesn't actually do squat except interpret EcmaScript in a little isolated console, so don't get your hopes up.
Reminder — here's the Ejacs URL: http://code.google.com/p/ejacs - enjoy!
And with that, I'm off to find some Nuka-Cola Quantum. I just wish those bastards hadn't capped me at level 20.
Materi Komposisi & Invers Fungsi
Untuk Haryo dan teman-teman yang membutuhkan materi komposisi fungsi dan fungsi invers silahkan didownload saja. Semoga membantu...
Materi Komposisi & Invers Fungsi
Salam,
HJS
Materi Komposisi & Invers Fungsi
Salam,
HJS
Soal Minggu Ini 17112008
Tentukan himpunan semua bilangan real yang kuadratnya lebih kecil atau sama dengan dua kali bilangan tersebut ditambah tiga.
Selamat Mencoba!
Selamat Mencoba!
Jumat, 14 November 2008
Soal Ujian Nasional 2007
Sebenarnya kumpulan soal - soal Ujian Nasional yang saya ketik telah saya klasifikasikan berdasarkan bab, sehingga diharapkan setiap siswa yang mempelajari soal - soal tersebut bisa melihat variasi soal yang keluar setiap tahunnya.Selain itu diharapkan juga siswa dapat dengan jeli melihat kelemahan dari setiap soal, sehingga setiap soal bisa dikerjakan dengan waktu yang relatif singkat. Nah kalau
Buku Tamu
Selamat Datang di blog Matematika SMA.Sedianya blog ini akan terus dikembangkan agar dapat turut berperan serta dalam pembelajaran matematika di dunia maya. Saran dan kritik Anda semua terhadap blog ini sangat kami nantikan, agar kedepannya blog ini bisa semakin lebih baik.Terima kasih.Untuk anda yang ingin menghubungi saya dapat melihat kontak saya ( klik disini )TtdMatematika SMA
Kamis, 13 November 2008
IMSO: Siswa SD Indonesia Raih Juara Umum
Mataram, Kompas - Tim sekolah dasar Indonesia menjadi juara umum International Mathematics and Science Olympiad atau IMSO 2008, yang berlangsung di Mataram, 8-14 November 2008. Pada kegiatan yang sudah berlangsung untuk kelima kalinya ini, Indonesia menjadi juara umum setelah meraih delapan medali emas, 10 perak, dan 13 perunggu.
Tim Indonesia, dalam kompetisi bidang matematika, meraih empat emas, lima perak dan lima perungu. Adapun untuk bidang ilmu pengetahuan alam atau sains, tim Indonesia meraih empat medali emas, lima perak, dan delapan perunggu.
Dua anggota tim Indonesia, yaitu Stefano Chiesa Suryanto dan Valentino Sudaryo, masing-masing meraih Eksplorasi Terbaik Bidang Matematika dan Percobaan Terbaik di bidang IPA.
Peserta terbaik untuk masing-masing bidang diperoleh murid sekolah dasar asal Taiwan, Yung Kuang Wang (Matematika) dan murid asal Singapura, Yeo Jia Qi (IPA).
Valentino mengaku sangat senang menerima penghargaan ini. Dirinya tidak menyangka akan menerima penghargaan ini karena persaingan antarpeserta cukup ketat. Beberapa murid sekolah dasar asal Singapura, Hongkong, dan Taiwan, menurutnya, menjadi pesaing ketatnya pada kompetisi kali ini.
Kompetisi tahunan yang diselenggarakan Direktorat Pembinaan Taman Kanak-kanak dan Sekolah Dasar Direktorat Jenderal Manajemen Pendidikan Dasar dan Menengah kali ini diikuti 171 peserta dari Brunai, Hongkong, Taiwan, Sri Lanka, Nigeria, Indonesia, Malaysia, Singapura, Thailand, dan Filipina.
”Kemenangan tim Indonesia sudah diprediksikan sebelumnya. Dari berbagai latihan dan uji coba, banyak siswa kita yang memiliki kemampuan di atas rata-rata,” ujar Mudjito AK, Direktur Pembinaan TK dan SD Depdiknas.
Pada ajang IMSO tersebut, Indonesia mengirimkan 139 siswa SD dengan rincian 72 siswa untuk tim Matematika dan 67 siswa untuk tim IPA.
Husaini Wardi, Kepala subdirektorat Program Direktorat Pembinaan TK dan SD Depdiknas, mengatakan bahwa pe- serta disaring ketat dari seluruh wilayah Indonesia. (RUL/MHD/ELN)
Tim Indonesia, dalam kompetisi bidang matematika, meraih empat emas, lima perak dan lima perungu. Adapun untuk bidang ilmu pengetahuan alam atau sains, tim Indonesia meraih empat medali emas, lima perak, dan delapan perunggu.
Dua anggota tim Indonesia, yaitu Stefano Chiesa Suryanto dan Valentino Sudaryo, masing-masing meraih Eksplorasi Terbaik Bidang Matematika dan Percobaan Terbaik di bidang IPA.
Peserta terbaik untuk masing-masing bidang diperoleh murid sekolah dasar asal Taiwan, Yung Kuang Wang (Matematika) dan murid asal Singapura, Yeo Jia Qi (IPA).
Valentino mengaku sangat senang menerima penghargaan ini. Dirinya tidak menyangka akan menerima penghargaan ini karena persaingan antarpeserta cukup ketat. Beberapa murid sekolah dasar asal Singapura, Hongkong, dan Taiwan, menurutnya, menjadi pesaing ketatnya pada kompetisi kali ini.
Kompetisi tahunan yang diselenggarakan Direktorat Pembinaan Taman Kanak-kanak dan Sekolah Dasar Direktorat Jenderal Manajemen Pendidikan Dasar dan Menengah kali ini diikuti 171 peserta dari Brunai, Hongkong, Taiwan, Sri Lanka, Nigeria, Indonesia, Malaysia, Singapura, Thailand, dan Filipina.
”Kemenangan tim Indonesia sudah diprediksikan sebelumnya. Dari berbagai latihan dan uji coba, banyak siswa kita yang memiliki kemampuan di atas rata-rata,” ujar Mudjito AK, Direktur Pembinaan TK dan SD Depdiknas.
Pada ajang IMSO tersebut, Indonesia mengirimkan 139 siswa SD dengan rincian 72 siswa untuk tim Matematika dan 67 siswa untuk tim IPA.
Husaini Wardi, Kepala subdirektorat Program Direktorat Pembinaan TK dan SD Depdiknas, mengatakan bahwa pe- serta disaring ketat dari seluruh wilayah Indonesia. (RUL/MHD/ELN)
Minggu, 09 November 2008
Soal Minggu Ini 10112008
Seorang ayah dan anak bekerja bersama dapat mengecat rumah mereka dalam waktu 8 hari. Jika bekerja sendiri, anak tersebut membutuhkan waktu 12 jam lebih lama dari sang ayah untuk mengecat rumah mereka. Berapa lama waktu yang dibutuhkan oleh sang ayah jika ia bekerja sendiri mengecat rumah tersebut?
Tangram
Tangram adalah permainan yang paling tua yang dikenal dalam matematika. Permainan ini dikembangkan pertama kali di negeri Cina dan sering disebut dengan puzzle Cina. Tangram berasal dari kata TANG + GRAM. Istilah ini pertama kali dikenalkan oleh Thomas Hill dalam bukunya Geometrical Puzzle for the Youth pada tahun 1848.
Tangram terdiri dari 5 buah segitiga, 1 persegi, dan 1 jajar genjang. Tangram banyak tersedia di pasaran, tetapi dapat juga dengan mudah dibuat sendiri. Dengan memotong kertas menurut garis-garis berwarna biru, maka akan diperoleh tangram yang dimaksud.
Apabila bagian-bagian tangram diberi warna yang berbeda-beda maka akan diperoleh tangram sebagai berikut.
Bisakah kamu membentuk gambar berikut ini.
Tangram terdiri dari 5 buah segitiga, 1 persegi, dan 1 jajar genjang. Tangram banyak tersedia di pasaran, tetapi dapat juga dengan mudah dibuat sendiri. Dengan memotong kertas menurut garis-garis berwarna biru, maka akan diperoleh tangram yang dimaksud.
Apabila bagian-bagian tangram diberi warna yang berbeda-beda maka akan diperoleh tangram sebagai berikut.
Bisakah kamu membentuk gambar berikut ini.
Senin, 03 November 2008
Pembahasan Integral
Sebenarnya keinginan untuk upload tentang pembahasan integral sudah bisa dilakukan beberapa hari yang lalu, tetapi karena terbentur oleh banyak aktivitas yang terkadang membuat saya tidak sempat untuk ngeblog maka baru hari ini saya bisa upload pembahasan tentang intagral.Itupun setelah lama dikerjakan belum sepenuhnya rampung, ini disebabkan jumlah soalnya yang relatif banyak dan penggunaan
Minggu, 02 November 2008
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