getting http 500 after registration =( On Thursday, July 26, 2012 10:59:46 PM UTC+3, Aaron Lebo wrote: > > Hello! > > Sometime around 2 and a half months ago, I started to work on a new > project using Clojure. I've been using Python heavily for about 6 six years > working for a small direct mail company and before that started programming > with Ruby on Rails. This new project was something out of left field, so I > had different options on what technology to use. I ended up choosing > Clojure, and my work on the site has been my first real experience using a > lisp, Clojure, and the JVM. I'd like to share my experiences and how that > has differed with my previous Python work. > > Before that, I'd like to make a little plug for my site. It is called > kodefund <http://www.kodefund.com> (www.kodefund.com). The basic idea is > to take the familiar Kickstarter model but to really focus on applying that > to open source development. I feel that previous crowdfunding efforts have > shown that there is an interest by developers to fund projects that they > are enthusiastic about. When this works, everyone wins: the developer > working on the project can devote their full time and effort on the actual > project and still make a living and others get the benefits of the open > source software. I feel like it is preferable over selling licenses to > proprietary software or other efforts. > > So, every project on kodefund is required to be open source. This > differentiates it from other crowdfunding sites, and helps to apply a > filter: you know what you are getting when you go there instead of seeing > dozens of projects for unrelated stuff. > > One other difference is that you can also start a project which is more or > less a "reverse" Kickstarter. This allows you to take an idea for a project > or issue you want fixed, raise funding, and find someone who will actually > implement the project. Other users get to submit "applications" and you > choose from them to find the most capable candidate. Once you chose an > application, that person takes over the project. > > Finally, one other push I want to make is to open up proprietary software. > Maybe your company has written some software in-house, but there's no real > incentive to release it. What if you could crowdfund the software, get paid > to release it, and the open source community as a whole could benefit from > that? > > I feel like crowdfunding and open source software are an ideal fit. > > I'm getting off track here. I'll shift to my actual experiences using > Clojure. I was more than a little nervous about using the JVM. It always > seemed like some huge, scary thing, and digging into Java libraries was not > something I wanted to do. Something which resolved this was leiningen. I > feel like it is absolutely brilliant, and it really makes adding libraries > to your project a non-issue. Things have slowly changed in Python, but it > used to be that downloading dependencies was a global process and you ended > up with a site-packages that was full of dozens of old libraries that you > used for other projects. Being able to specify in my project.clj file > exactly which libraries I need and those getting downloaded automatically > is a really nice feature that I will look for similar functionality in > other languages from now on. > > I was also pleasantly surprised by the library availability. The vast > majority of things that I needed such as oauth2 support and such already > have decent Clojure wrappers. When I did drop down into Java, I found that > to be painless. The JVM really does have a wide swath of functionality > already available. Some of the things that I ended up using were email > libraries, date formatting libraries, and an rss feed generator. There > never was a point where I felt like I was going to have to just roll things > by hand. Most of the hard work has been done. > > Considering the language itself, one of the first things I noticed (or > didn't) was the parentheses. I don't remember when, but they simply are a > non-issue after a short amount of time. One slight thing I did have a > problem with was that inserting a parenthesis at the wrong place could > completely alter the flow of code and it was not immediately obvious. This > is not an issue when you are closing off a line or two of expressions, but > when you are halfway down the page, insert a paren and everything breaks, > it could get frustrating. This is probably resolved through better editor > usage. I unfortunately could never get emacs with clojure-mode and goodies > working properly on my Windows machine, so I ended up using the > counterclockwise Eclipse plugin. It was not a horrible experience but > things such as auto-indenting a large block of code was something I never > figured out. > > Continuing on the surface, some of my favorite parts of the language are > little syntax additions. I absolutely love the syntax for anonymous > functions. Python obviously has limitations with lamdas anyway, but in > Clojure, having a block of code like: (do (println test) (+ 3 3)) and being > able to instantly convert that to an anonymous function by sticking a # on > the front is really nice. Not having to explicitly name function arguments > helps as well. > > Destructuring syntax is amazing. Being able to break a map or a vector > down and bind numerous variables in a let or function is something that > simply is not easily done in Python without some magic. It was nice to have > a function definition of something like (defn index [request] ...) in a > view and to be able to grab relevant needed variables using the {:keys ...} > syntax. > > The language is full of these little bits that are really convenient, and > I was constantly surprised by something new which significantly reduced the > amount of code I was writing. Having used it, it is straight up painful in > my opinion to write markup in anything else. The -> operator, hash maps as > functions, etc. > > One thing which surprised my was the macros. Initially I didn't use a > single macro in my code, and I really couldn't figure out why the were so > lauded and considered important by lots of lisp developers. That changed > later in the project when I noticed a familiar pattern in my code. The > basic problem was that pretty much every single web request has a familiar > flow: > > Does the resource exist? If not, throw a 404. > Does the user have the proper permissions to access the resource? If not, > redirect to login or throw up a permission denied page. > Is this a post? If not, render a form. > If it is and the post is valid, do some work and redirect. If not valid, > render the form. > > This got used over and over. In Django you often see this in the form of: > > def index(request): > item = get_object_or_404(...) > form = Form(request, item) > if request.method == 'POST' and form.valid(): > do stuff > redirect() > render('index.html', dict(form=form)) > > This isn't the worst thing in the world, but its just extra code that gets > in the way of the literal intent of the code. When I noticed this pattern I > ended up writing a macro which handled the resource check, the auth check, > the validation check, the redirection, etc, for me. Once I got to this > point, I really "got" macros and their power. You simply don't have the > ability to implement your own flow control this easily in Python. > > Now, to thinking and working functionally. Python is imperative in parts. > One of my favorite parts in it is the list comprehensions, which can be > very functional. But for loops and destructive updates abound. Coding > without for and accumulators was maybe the most difficult adjustment for > me. However, once I started using map (with the aforementioned excellent > anon function syntax), I started wanting to use it everywhere I could, > because the concept was so simple. The same goes for reduce. Much of the > pain of lacking destructive updates is mitigated with things like > update-in, and such. > > I guess for me the real question is whether programming functionally > actually reduces the number of errors as some functional advocates put > forward. The problem is that it is so damn hard to objectively compare the > two. Did I have more errors when I was programming in Python compared to > Clojure? I'd say most of my errors actually came from unfamiliarity of > libraries or functionality. The idea that errors can be reduced is > interesting, but I'm not ready to fully commit to that suggestion unless we > really see hard data. I do know that there are places where destructive > updates would be convenient, but I can appreciate basis of programming > functionally. > > Was there anything I missed when using Clojure compared to Python? The > libraries seem to be a wash, the languages themselves are comparable. If > anything I did want maturity in some of the libraries. For example, noir > has an excellent error validation library. However, compared to Python > libraries which do validation and conversion, I found myself writing and > debugging extra functionality that I had to implement. I found myself > digging around in github repos to actual read code instead of documentation > a lot more than I ever did with Python. Obviously these are just issues of > time, and they'll improve. Clojure docs and the cheatsheet help a lot, > though. > > Stacktraces can take a while to get used to, and some of the error > messages are cryptic. I can't say how many hours I spent figuring out why > #([:key "test"]) wasn't working (you can't place a vector literal directly > inside an anonymous function like this. Maybe that should have been obvious > to me, but once I ran across these issues and understood them, the pain of > understanding stacktraces was mitigated by a large margin. > > I guess if there is anything I'd love to see is some kind of style guide. > Python has the PEP8 style guide, which more or less suggests how code > should be written, not that it has to be written that way. There were lots > of times I found myself wondering whether the "right" way was to indent the > if form after the conditional or first argument, or whether it was > considered "bad" form to nest multiple lets, and how that should be > handled. The current cheat sheet is similar, but its not very prescriptive. > I'd love to see something which suggests how common tasks should be done, I > feel like it might help newbies like me feel more at ease. Does such a > thing like PEP 8 exist for Clojure? > > Well, those are some of my notes on using Clojure. I feel a little > embarrassed writing this up because I feel like someone will pick it to > death, and I'm wish I could delve further into hard details instead of > dwelling so much on little syntax differences. It has been a fun, useful > learning experience, anyway. I feel like anyone who has not worked with a > lisp or a functional programming language owes it to their own development > to work with Clojure, it really does help you to understand the whats and > whys of the JVM, macros, and functional programming. > > I'd especially love to see, kodefund, used by the Clojure community. I > feel like it is a great way to get new libraries off the ground, or to find > people to fix bugs, or even to open up previously closed software. > > If there was a project that you were considering putting on Kickstarter or > one of the other crowdfunding sites, please consider kodefund. Unlike the > bigger sites, you will have my full attention to your project, and I'm more > than willing to work with you to improve and change parts of the site which > make crowdfunding more suitable to open source projects. > > I've worked really hard to make things as simple as possible. You can > start or fund a project no matter where you live, all that is needed to > make a pledge is a credit card, and github, twitter, facebook, google are > all supported to sign up. Give it a try, let me know what you think. I've > tried to explain the rationale further here: > http://www.kodefund.com/about/ > > So, if you've got any questions about kodefund <http://www.kodefund.com>or > Python/Clojure, I'm happy to answer them. Thanks to those who have spent > their time making this such a useful language! > >
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