6 ms·

Show HN: Clojure by Example

184 points by kimh 11y ago

abc_lisper 11y ago
Good job Man! Bookmarked.
josebaezmedina 11y ago
It reminds me to http://learnxinyminutes.com/docs/clojure/ http://learnxinyminutes.com/docs/clojure/ but prettier.
maelito 11y ago
Very pleasant to read
jonnybgood 11y ago
Would be awesome if interactive like the interactive SICP[0] [0] http://xuanji.appspot.com/isicp http://xuanji.appspot.com/isicp
- fierycatnet 11y ago
  Woah. I've been wanting to finish SICP book along with MIT lectures and this site looks like another great addition. This gives me a boost in motivation to finish the book. If someone ever comes up for something like this for Clojure then it would be incredibly awesome.
- elangoc 11y ago
  Whoa! ISICP looks really cool! You know, the exercise sections of ISICP remind me a lot of the interactive Clojure exercises at 4Clojure.com. 4Clojure.com has a link to the github repo of the software used to create the site.
hajims 11y ago
This should be posted over to r/clojure
- icey 11y ago
  That's a great idea; just posted it over there and added it to the sidebar.
elwell 11y ago
Looks cool. Code indentation error/confusion at http://kimh.github.io/clojure-by-example/#future http://kimh.github.io/clojure-by-example/#future though.
fierycatnet 11y ago
Cool, thanks! Looks like a nice reference.
nerd_stuff 11y ago
This is a great project! I believe there's a lack of clarity in the let form explanation: =>(let [object "light"] => (let [object "darkness"]) => (println (str "God said let there be " object))) God said let there be light nil 'object' is overwritten but only within the second let form: =>(let [object "light"] => (let [object "darkness"] => (println (str "God said let there be " object)))) God said let there be darkness nil or even: =>(let [object "light"] => (println (str "God said let there be " object)) => (let [object "darkness"] => (println (str "God said let there be " object)))) God said let there be light God said let there be darkness nil The reason for this is the let form uses lexical scoping. In other words it creates a new frame which includes the bindings declared in the square brackets. When 'object' is evaluated its binding is looked for in the current frame, then the frame that called that frame and all the way out into the global namespace stopping when a binding is found. See also: http://stackoverflow.com/questions/1774417/scoping-rules-in-clojure http://stackoverflow.com/questions/1774417/scoping-rules-in-...
- fnordsensei 11y ago
  This would be better for illustrating that object is not overweritten, I think: =>(let [object "light"] => (let [object "darkness"] => (println (str "God said let there be " object))) => (println (str "God said let there be " object))) God said let there be darkness God said let there be light nil
  - kimh 11y ago
    Thanks for this. I added your example with slightly different form!
- deleted 11y ago
  [deleted]
- kimh 11y ago
  Thanks for your feedback! I think I could make it better. http://kimh.github.io/clojure-by-example/#scope http://kimh.github.io/clojure-by-example/#scope
hoprocker 11y ago
Lovely. A nice addition would be a floating REPL to try things out as you go along, maybe at the bottom of the screen with a dash of transparency. (I know I know, there are plenty of other ways to access a Clojure REPL!)
lewisl9029 11y ago
For those who prefer learning in a more passive manner, I've found these sets of screencasts on the Clojure Koans quite useful too. http://www.clojurescreencasts.com/koans-walkthrough/01.html http://www.clojurescreencasts.com/koans-walkthrough/01.html
melipone 11y ago
Remind me of the little schemer. How about a "The little clojurist" book?
mayneack 11y ago
This is super helpful. Reminds me of bropages: http://bropages.org/ http://bropages.org/
pvdebbe 11y ago
Great execution, but the indentation is wonky at times, making it difficult to see the idea.
dvliman 11y ago
this is exactly how intro to programming language should be (for people who already know other languages)
elangoc 11y ago
I love it! The target audience is people with prior programming experience. It's important to know the target audience, either as a writer or reviewer. The tutorial webpage is simple and effective with a gradual progression in concept difficulty. I hope we have more things like this! Thanks!
thomas11 11y ago
http://www.4clojure.com/ http://www.4clojure.com/ should also be mentioned here. I had a lot of fun there.
TickleSteve 11y ago
Clojure has always been slightly disappointing for me... The principles behind its design are all sound and Rich Hickey deserves credit for putting in the hard thought behind it. ... but.... the reality seems to be of a really under performing language. The forums are consistently full of people with 'why is this slow?' to which the solution is always 'Give it more hints' or 'do it in a more Java like way'. Unfortunately the Clojure stack seems not to have much mechanical sympathy (despite its best intentions). It seems the natural/idiomatic way to use Clojure results in far too much dynamic behavior to be performant. Clojure may scale well, but its inherent bad performance (without lots of work) is a major downside. I forget who said this, but it seems very appropriate to Clojurists... "Show me you can use one machine well before you get another..."
- codeshaman 11y ago
  I aggree. I love the language and concepts, but at some point, after two months of learning it, I've got fed up with the slugishness of the whole thing and gave up because I have no idea what to do with it. I also found it a very difficult language to learn. I felt like I was taking baby steps every day, although I was giving it all I could. I felt stupid and frustrated to the point that I'm actually considering quitting the profession, because, well, I'm not good enough for this. Contrast that with Objective-C which I learned last year - it took me a couple of weeks to become profficient and start writing real world, commercial apps which I can sell. Maybe 15 years of daily C++ programming has had something to do with it, but still. I struggle to imagine a practical project which I could use clojure for. Front end, user-facing apps, utilities, system tools - forget it - an app takes 15 seconds to load and uses gigabytes of RAM. Backend - maybe, but there are a lot of other languages and frameworks out there which are really powerful and have huge communities. So I don't know, I really love clojure, but the JVM just doesn't cut it for me. I want a C++ version of Clojure, which I was thinking about starting every single day I was learning it.
  - dasmoth 11y ago
    https://github.com/pixie-lang/pixie https://github.com/pixie-lang/pixie could be worth a look. That said, "add more type hints" hasn't generally been my experience of Clojure. If anything, it tends to be an indication that you've already gone a bit far down the path of "doing things the Java way".
kimh 11y ago
If the site looks cool and slick to you, then you should give a star to https://github.com/tripit/slate https://github.com/tripit/slate which I used to create the site. I found Slate is very easy to use and customize!!

184 points by kimh 11y ago

abc_lisper 11y ago

Good job Man! Bookmarked.

josebaezmedina 11y ago

It reminds me to http://learnxinyminutes.com/docs/clojure/ http://learnxinyminutes.com/docs/clojure/ but prettier.

maelito 11y ago

Very pleasant to read

jonnybgood 11y ago

Would be awesome if interactive like the interactive SICP[0] [0] http://xuanji.appspot.com/isicp http://xuanji.appspot.com/isicp

fierycatnet 11y ago
Woah. I've been wanting to finish SICP book along with MIT lectures and this site looks like another great addition. This gives me a boost in motivation to finish the book. If someone ever comes up for something like this for Clojure then it would be incredibly awesome.
elangoc 11y ago
Whoa! ISICP looks really cool! You know, the exercise sections of ISICP remind me a lot of the interactive Clojure exercises at 4Clojure.com. 4Clojure.com has a link to the github repo of the software used to create the site.

hajims 11y ago

This should be posted over to r/clojure

icey 11y ago
That's a great idea; just posted it over there and added it to the sidebar.

elwell 11y ago

Looks cool. Code indentation error/confusion at http://kimh.github.io/clojure-by-example/#future http://kimh.github.io/clojure-by-example/#future though.

fierycatnet 11y ago

Cool, thanks! Looks like a nice reference.

nerd_stuff 11y ago

This is a great project! I believe there's a lack of clarity in the let form explanation: =>(let [object "light"] => (let [object "darkness"]) => (println (str "God said let there be " object))) God said let there be light nil 'object' is overwritten but only within the second let form: =>(let [object "light"] => (let [object "darkness"] => (println (str "God said let there be " object)))) God said let there be darkness nil or even: =>(let [object "light"] => (println (str "God said let there be " object)) => (let [object "darkness"] => (println (str "God said let there be " object)))) God said let there be light God said let there be darkness nil The reason for this is the let form uses lexical scoping. In other words it creates a new frame which includes the bindings declared in the square brackets. When 'object' is evaluated its binding is looked for in the current frame, then the frame that called that frame and all the way out into the global namespace stopping when a binding is found. See also: http://stackoverflow.com/questions/1774417/scoping-rules-in-clojure http://stackoverflow.com/questions/1774417/scoping-rules-in-...

fnordsensei 11y ago
This would be better for illustrating that object is not overweritten, I think: =>(let [object "light"] => (let [object "darkness"] => (println (str "God said let there be " object))) => (println (str "God said let there be " object))) God said let there be darkness God said let there be light nil
- kimh 11y ago
  Thanks for this. I added your example with slightly different form!
deleted 11y ago
[deleted]
kimh 11y ago
Thanks for your feedback! I think I could make it better. http://kimh.github.io/clojure-by-example/#scope http://kimh.github.io/clojure-by-example/#scope

hoprocker 11y ago

Lovely. A nice addition would be a floating REPL to try things out as you go along, maybe at the bottom of the screen with a dash of transparency. (I know I know, there are plenty of other ways to access a Clojure REPL!)

lewisl9029 11y ago

For those who prefer learning in a more passive manner, I've found these sets of screencasts on the Clojure Koans quite useful too. http://www.clojurescreencasts.com/koans-walkthrough/01.html http://www.clojurescreencasts.com/koans-walkthrough/01.html

melipone 11y ago

Remind me of the little schemer. How about a "The little clojurist" book?

mayneack 11y ago

This is super helpful. Reminds me of bropages: http://bropages.org/ http://bropages.org/

pvdebbe 11y ago

Great execution, but the indentation is wonky at times, making it difficult to see the idea.

dvliman 11y ago

this is exactly how intro to programming language should be (for people who already know other languages)

elangoc 11y ago

I love it! The target audience is people with prior programming experience. It's important to know the target audience, either as a writer or reviewer. The tutorial webpage is simple and effective with a gradual progression in concept difficulty. I hope we have more things like this! Thanks!

thomas11 11y ago

http://www.4clojure.com/ http://www.4clojure.com/ should also be mentioned here. I had a lot of fun there.

TickleSteve 11y ago

Clojure has always been slightly disappointing for me... The principles behind its design are all sound and Rich Hickey deserves credit for putting in the hard thought behind it. ... but.... the reality seems to be of a really under performing language. The forums are consistently full of people with 'why is this slow?' to which the solution is always 'Give it more hints' or 'do it in a more Java like way'. Unfortunately the Clojure stack seems not to have much mechanical sympathy (despite its best intentions). It seems the natural/idiomatic way to use Clojure results in far too much dynamic behavior to be performant. Clojure may scale well, but its inherent bad performance (without lots of work) is a major downside. I forget who said this, but it seems very appropriate to Clojurists... "Show me you can use one machine well before you get another..."

codeshaman 11y ago
I aggree. I love the language and concepts, but at some point, after two months of learning it, I've got fed up with the slugishness of the whole thing and gave up because I have no idea what to do with it. I also found it a very difficult language to learn. I felt like I was taking baby steps every day, although I was giving it all I could. I felt stupid and frustrated to the point that I'm actually considering quitting the profession, because, well, I'm not good enough for this. Contrast that with Objective-C which I learned last year - it took me a couple of weeks to become profficient and start writing real world, commercial apps which I can sell. Maybe 15 years of daily C++ programming has had something to do with it, but still. I struggle to imagine a practical project which I could use clojure for. Front end, user-facing apps, utilities, system tools - forget it - an app takes 15 seconds to load and uses gigabytes of RAM. Backend - maybe, but there are a lot of other languages and frameworks out there which are really powerful and have huge communities. So I don't know, I really love clojure, but the JVM just doesn't cut it for me. I want a C++ version of Clojure, which I was thinking about starting every single day I was learning it.
- dasmoth 11y ago
  https://github.com/pixie-lang/pixie https://github.com/pixie-lang/pixie could be worth a look. That said, "add more type hints" hasn't generally been my experience of Clojure. If anything, it tends to be an indication that you've already gone a bit far down the path of "doing things the Java way".

kimh 11y ago

If the site looks cool and slick to you, then you should give a star to https://github.com/tripit/slate https://github.com/tripit/slate which I used to create the site. I found Slate is very easy to use and customize!!