Clojure Distilled

http://yogthos.github.io/ClojureDistilled.html

by nickmain • 12 years ago

168 51 12 years ago

yogthos.github.io

daveloyall2• 12 years ago

That link is down for me, but I think this is the same content?

http://yogthos.github.io/ClojureDistilled.html

sternenseemann• 12 years ago

also this works via rawgit: https://cdn.rawgit.com/yogthos/yogthos.github.com/master/Clo...

daveloyall2• 12 years ago

Noted, thanks!

jkrems• 12 years ago

But the "real" URL also would have proper CSS etc. and looks slightly less broken.

dang• 12 years ago

Thanks! We changed to that from https://rawgit.com/yogthos/yogthos.github.com/master/Clojure....

profil• 12 years ago

When using rawgit, please follow the owners request about using cdn.rawgit.com for anything that might result in heavy traffic. I guess links submitted to HN often results in heavy traffic.

https://rawgit.com/faq#diff-between-rawgit-and-cdn

infogulch• 12 years ago

So the url should be changed to this (which loads for me):

https://cdn.rawgit.com/yogthos/yogthos.github.com/master/Clo...

serve_yay• 12 years ago

Would it really be so difficult to redirect my request...

jdeisenberg• 12 years ago

It's a very good summary.

nelsonenzo• 12 years ago

correct link here https://cdn.rawgit.com/yogthos/yogthos.github.com/master/Clo...

arms3• 12 years ago

I'm currently learning Clojure. For all the "aha!" moments, there are plenty of "WTFs?", too. Not that it's a fault of the language, it's just that it requires a different way of looking at things. I've only skimmed this article, but look forward to reading it in depth later. Thanks!

I'd be interested if anyone has some similar pieces to share.

verisimilidude• 12 years ago

Most of my Clojure WTFs were not related to the language itself, but rather the tooling. This was years ago, but everyone used to say, "Before diving into Clojure, you should really learn emacs and all these other things first." I'm glad I ignored them and sputtered along in a text editor while learning the basics of the language, because I would've otherwise burnt out.

With apps like Light Table now available, maybe beginners have an easier ramp these days.

arms3• 12 years ago

Good to know! I started with emacs, but decided to use Light Table for now. Nothing against emacs, but I don't want to make things harder by learning a new language and a new editor at the same time. Aside from Light Table (and presumably Leiningen) do you have any other tooling recommendations?

programnature• 12 years ago

Definitely recommend people try Cursive Clojure, the clojure Intellij plugin. Much easier to use/setup than emacs IMHO. Lots of clojure people have been switching.

yogthos2• 12 years ago

I never got into Emacs myself, I started with Eclipse and then moved to Cursive (https://cursiveclojure.com/) which I simply can't recommend enough, I also use Light Table for some of my smaller projects.

The fact that you don't have to use Emacs to work with Clojure is a huge benefit in my opinion. Emacs takes a lot of investment to learn and use effectively, and not everybody has the time, nor the inclination to do that.

arms3• 12 years ago

So I'm about half way through it now. I'm really impressed with how much information it's conveying in a succinct form. I'm going through Clojure for the Brave and True, and think this supplements it nicely.

There are a few typos, but the most glaring one was the incomplete python code underneath the "Code Structure" heading:

l = [1, 2, 3, 4, 5]

for i in l i = i*i

for i in l if (i mod 2 == 0)

print l

I assume the author wanted to show how the list was mutated. And those conditionals need trailing colons :)

yogthos2• 12 years ago

thanks, I just fixed that, I'm not a python guy as you can tell :)

raspasov2• 12 years ago

My personal favorite editor is IntelliJ IDEA Community Edition + cursiveclojure.com plugin (not affiliated with the cursiveclojure.com people but highly recommend it). I don't come from an Emacs background but from what I've seen and heard from Emacs people is that it combines all the best parts of Emacs when it comes to Lisp code manipulation.

lemming• 12 years ago

I'm the developer of Cursive - thanks to you and others in this thread, I'm really glad you're all liking it!

killercup• 12 years ago

I'm not done reading but it seems like a very nice introduction to people not familiar with the function style of programming.

This is also one of the few document that can be converted from html to epub without much pain. It looks quite good with

    pandoc ClojureDistilled.html -o ClojureDistilled.epub --indented-code-classes=clojure

fdsary• 12 years ago

I love clojure, and dream of the day I can work with it.

But do you know why more people get into ruby or js? It's community is beginner friendly. Most texts on the subject of lisps feel like wannabe dissertations, preferably with the Computer Modern font and 5 pages long.

erichmond• 12 years ago

These links seem pretty beginner friendly to me.

http://tryclj.com/ http://www.braveclojure.com/ http://aphyr.com/posts/301-clojure-from-the-ground-up-welcom... http://clojurekoans.com/ http://www.4clojure.com/

oinksoft• 12 years ago

I would never suggest a programmer learn Clojure as their first language, because of the enormous Java stacktraces. Then there's the setup involved (Java, usually Leiningen) to get to "Hello, World" compared to Python or Ruby. Just too many places where the student can get seriously stuck. Clojure's strengths (immutable structures, expression freedom, macros, Java interop, JVM) are not relevant to the new programmer.

raspasov2• 12 years ago

Yes, the Java stack traces are probably the worst "ugly" thing in Clojure but from my experience the simplicity of syntax (not to be confused with familiarity, familiar != simple) makes it much easier for someone who's never programmed before to start writing Clojure code vs many other languages where there's a lot of syntax to that you simply need to "know" to get going.

Also, on a more advanced note, I've used https://github.com/ptaoussanis/timbre with great success to get nicely formatted and colored Clojure errors and stack traces.

akurilin• 12 years ago

Doesn't have to be just a dream, check out HN's Who's Hiring for September, plenty of opportunities to have your everyday work be in Clojure out there, including our company.

d_t_w• 12 years ago

I've been working with Clojure for 18 months now, after a bit more than 10 years of Java. I'm having so much fun I don't think I could ever go back.

Also, this is an excellent summary / introduction to key clojure concepts, well done to the author.

kjjw2• 12 years ago

Seconded. I was working with a mix of Java and Ruby for roughly a decade. I've been working full time with Clojure for about two years now, and on and off for a couple of years before that.

Fantastic introductory guide. Clojure really needs something like this. There are some good books on Clojure but I find they are aimed at either the determined beginner or the experienced (or both.) This though I feel I could pass around to anyone that wants to get an idea of what Clojure is about.

tim333• 12 years ago

The main link's stopped working with a message to use the cdn version instead:

https://cdn.rawgit.com/yogthos/yogthos.github.com/master/Clo...

sailfast• 12 years ago

I'm really enjoying reading this - thanks!

For those that don't want to tax the owner of rawgit - try github pages - it's just HTML, right? http://yogthos.github.io/ClojureDistilled.html

dschiptsov3• 12 years ago

I am really suggesting to try some classic Scheme course first, like my favorite CS61A by Brian Harvey, or that wonderful Racket-based course (what's the difference?) on Coursera by Gregor Kiczales (which is worth watching even if you are mere a brainwashed Java dev).

Another way is through pg's books, especially, of course, "On Lisp" and Arc tutorial and then arc.arc (original version from the 2009 arc3.tar which isn't cluttered with silly docstrings and other nonsense).

There is also the way of CL. For that there is pg's ANSI CL, but before that a much better "CL Language Concepts" from Symbolics (pdfs are available from bitsavers).

Then, perhaps, one will have slightly different view of what Clojure is really. Yes, it is a real marvel of software craftsmanship, especially that it was originally a solo effort, but no, there is no miracles in it.)

ExpiredLink• 12 years ago

even if you are mere a brainwashed Java dev

I see where you're coming from, SLW.

zak_mc_kracken• 12 years ago

which is worth watching even if you are mere a brainwashed Java dev

And people wonder why Lisp advocates have such a bad reputation.

AlexeyBrin2• 12 years ago

    which is worth watching even if you are mere a brainwashed Java dev

and this is why so many people are repelled by the Lisp (or Scheme) evangelism. I don't particularly like Java, but I use it for Android development. Calling people brainwashed because they are using Java is simply rude.

dschiptsov3• 12 years ago

In my opinion Java is the biggest fraud and waste in the history of IT (next comes SAP) - nothing but hype, ignorant parroting of silly memes by "managers" (so-called bandwagon and peer effects) lies, and taking advantage of ignorant.

People who "know no better" (cannot even visit the rosettacode.org, dismissed plain old C - these evil pointers!, Erlang - functional programming is for academy, or CL - not an enterprise level, etc, etc) are, well, brainwashed.

I am not blaming the people, I am just describing reality as I see it, and my view is by no means new or even "original".

Java was just a way to make money (in 2000s) like "derivatives traders" in the last 10 years. Same manipulations, same techniques.

For example, almost all of the very few popular apps I have installed on my Nexus4 are NDK apps - FB, Viber, Skype - you name it.

zeroyzeroa• 12 years ago

Extracting keys from maps into a definition, with common-lisp (using my macro defk)

(defk login (user pass) (and (string= user "Bob") (string= pass "secret")))

(login (list-to-hash '(user "Bob" pass "secret")) (list-to-hash '(user "Bob" pass "secret"))

Given the following definitions:

(defmacro defk(name h-list &rest body) `(defun ,name (h) (let ,h-list ,@(loop for k in h-list collect `(setq ,k (gethash (quote ,k) h))) ,@body)))

(defun list-to-hash(list) (let ((h (make-hash-table))) (loop for (k v) on list by #'cddr do (setf (gethash k h) v)) h))

malisper• 12 years ago

It's probably more idiomatic to implement something similar to the with-slots macro by using symbol-macrolet:

  (defmacro with-keys (keys table &body body)
    (let ((gtable (gensym)))
      `(let ((,gtable ,table))
         (symbol-macrolet ,(loop for k in keys
                                 collect `(,k (gethash ',k ,gtable)))
           ,@body))))

This way you can both access and set the keys:

  CL-USER> (defparameter *table* (make-hash-table))
  *TABLE*
  CL-USER> (setf (gethash 'a *table*) 10
                 (gethash 'b *table*) 20)
  20
  CL-USER> (with-keys (a b) *table*
             (list a b))
  (10 20)
  CL-USER> (with-keys (a b) *table*
             (setf a 100
                   b 200))
  200
  CL-USER> (list (gethash 'a *table*)
                 (gethash 'b *table*))
  (100 200)

If you really want to destructure a hash-table when its an argument, it is not much harder to write a new version of defun on top of with-keys or zeroyzeroa's solution (his/hers only takes a single argument).

fnordsensei• 12 years ago

  Higher order functions can be easily chained 
  together to create complex transformations:

  (filter even?
    (map #(* 3 %) [1 2 3 4 5])) 
  =>(6 12)

This will need to be updated to make use of transducers, I guess.

rbanffy• 12 years ago

Only if it enhances the poetic value.

Clojure Distilled

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