Introduction to Clojure • Hacker News Board

Re: Introduction to Clojure

#11

Post by gruseom » Sat, Oct 17, 2009, 3:35 PM UTC

dreish wrote: post #9

jacquesm wrote: post #8

Earlier quoted context omitted.

which suggests the use of a 'close all open parens' token to cut down on all the )))))) stuff at the end of a line, which can get really tedious, especially when editing in 'dumb' editors.

That's not much help when you want to close all but one or two. The solution is to use the right tool for the job. Emacs has something called paredit-mode that relieves you of having to type the closing parens.

paredit-mode

Yes! I can't do without it now. BTW somebody told me Paredit is a port of the old Interlisp structured editor.

There's also http://news.ycombinator.com/item?id=877386, if you haven't seen it.

Re: Introduction to Clojure

#12

Post by alrex021 » Sat, Oct 17, 2009, 4:14 PM UTC

dreish wrote: post #5

Don't arrange your closing parens the way the author of this article has unless you want to look like a clueless noob. Edit: There are other style problems with this article. Worst is probably this one: Bad: (map (fn [x] (fibonacci x)) [1 2 3 5 6 7 8 9 10]) Good: (map fibonacci (range 1 11))

Absolutely right. Don't arrange your parens to fall separately like author does on new lines. Let the parens flow after one another.

The way your parens should flow:

  (def factorial
    (fn [n]
      (loop [cnt n acc 1]
        (if (zero? cnt)
            acc
          (recur (dec cnt) (* acc cnt))))))

The author doesn't take an idiomatic approach to programming in Clojure in most of his code snippets.

[edit]

Throwing java.lang.Exception if a condition is not meat in your clojure functions? Don't do this either!!!

Re: Introduction to Clojure

#13

Post by dreish » Sat, Oct 17, 2009, 4:19 PM UTC

gruseom wrote: post #11

dreish wrote: post #9

Earlier quoted context omitted.

That's not much help when you want to close all but one or two. The solution is to use the right tool for the job. Emacs has something called paredit-mode that relieves you of having to type the closing parens.

paredit-mode Yes! I can't do without it now. BTW somebody told me Paredit is a port of the old Interlisp structured editor. There's also http://news.ycombinator.com/item?id=877386 , if you haven't seen it.

I'm glad I took the plunge, too. At first, it seemed like a really bad idea -- far too awkward and unfamiliar for the minor advantage of automatically inserting closing parens. I kept at it mainly out of an attraction to the novel and quirky for long enough to discover that its biggest advantages aren't from not having to type ")" -- they're for things like barf, slurp, splice, and the S-expression-aware kill-line.

Whenever I'm programming in a non-Lisp language, I really miss those kinds of editor features that are enabled by having an idiot-simple syntax.

Re: Introduction to Clojure

#14

Post by mahmud » Sat, Oct 17, 2009, 4:27 PM UTC

dreish wrote: post #5

Don't arrange your closing parens the way the author of this article has unless you want to look like a clueless noob. Edit: There are other style problems with this article. Worst is probably this one: Bad: (map (fn [x] (fibonacci x)) [1 2 3 5 6 7 8 9 10]) Good: (map fibonacci (range 1 11))

Clojure has the highest percentage of "noob" users of any language. It's just 2 years old and everybody is pretty much wetting their feet with it just now.

Re: Introduction to Clojure

#15

Post by alrex021 » Sat, Oct 17, 2009, 4:32 PM UTC

mahmud wrote: post #14

dreish wrote: post #5

Don't arrange your closing parens the way the author of this article has unless you want to look like a clueless noob. Edit: There are other style problems with this article. Worst is probably this one: Bad: (map (fn [x] (fibonacci x)) [1 2 3 5 6 7 8 9 10]) Good: (map fibonacci (range 1 11))

Clojure has the highest percentage of "noob" users of any language. It's just 2 years old and everybody is pretty much wetting their feet with it just now.

Very true. But then the author of the article needs to get his feet a lot more wet because its plain and simply bad code.

Re: Introduction to Clojure

#16

Post by jacquesm » Sat, Oct 17, 2009, 6:14 PM UTC

alrex021 wrote: post #12

dreish wrote: post #5

Don't arrange your closing parens the way the author of this article has unless you want to look like a clueless noob. Edit: There are other style problems with this article. Worst is probably this one: Bad: (map (fn [x] (fibonacci x)) [1 2 3 5 6 7 8 9 10]) Good: (map fibonacci (range 1 11))

Absolutely right. Don't arrange your parens to fall separately like author does on new lines. Let the parens flow after one another. The way your parens should flow: (def factorial (fn [n] (loop [cnt n acc 1] (if (zero? cnt) acc (recur (dec cnt) (* acc cnt)))))) The author doesn't take an idiomatic approach to programming in Clojure in most of his code snippets. [edit] Throwing java.lang.Exception if a condition is n…

> Throwing java.lang.Exception if a condition is not meat in your clojure functions? Don't do this either!!!

What's the proper way of doing that in clojure ?

Re: Introduction to Clojure

#17

Post by cema » Sat, Oct 17, 2009, 6:53 PM UTC

mahmud wrote: post #14

dreish wrote: post #5

Don't arrange your closing parens the way the author of this article has unless you want to look like a clueless noob. Edit: There are other style problems with this article. Worst is probably this one: Bad: (map (fn [x] (fibonacci x)) [1 2 3 5 6 7 8 9 10]) Good: (map fibonacci (range 1 11))

Clojure has the highest percentage of "noob" users of any language. It's just 2 years old and everybody is pretty much wetting their feet with it just now.

This is true, but the style of the code layout follows Lisp tradition, which may be more than 50 years old! :-)

Re: Introduction to Clojure

#18

Post by licoresse » Sat, Oct 17, 2009, 7:03 PM UTC

jacquesm wrote: post #16

alrex021 wrote: post #12

Earlier quoted context omitted.

Absolutely right. Don't arrange your parens to fall separately like author does on new lines. Let the parens flow after one another. The way your parens should flow: (def factorial (fn [n] (loop [cnt n acc 1] (if (zero? cnt) acc (recur (dec cnt) (* acc cnt)))))) The author doesn't take an idiomatic approach to programming in Clojure in most of his code snippets. [edit] Throwing java.lang.Exception if a condition is n…

> Throwing java.lang.Exception if a condition is not meat in your clojure functions? Don't do this either!!! What's the proper way of doing that in clojure ?

Like you saw, but it's not idiomatic to do so

Re: Introduction to Clojure

#19

Post by licoresse » Sat, Oct 17, 2009, 7:04 PM UTC

jacquesm wrote: post #8

dreish wrote: post #7

Earlier quoted context omitted.

Yes, which is why it is a newbie signal. A Lisp programmer with more than about three weeks of experience doesn't look at parentheses or try to match them up with each other. You know the function has ended because the next line of code has no indentation.

which suggests the use of a 'close all open parens' token to cut down on all the )))))) stuff at the end of a line, which can get really tedious, especially when editing in 'dumb' editors.

Who would edit a lisp language in a dumb editor?

Re: Introduction to Clojure

#20

Post by alrex021 » Sat, Oct 17, 2009, 7:17 PM UTC

jacquesm wrote: post #16

alrex021 wrote: post #12

Earlier quoted context omitted.

Absolutely right. Don't arrange your parens to fall separately like author does on new lines. Let the parens flow after one another. The way your parens should flow: (def factorial (fn [n] (loop [cnt n acc 1] (if (zero? cnt) acc (recur (dec cnt) (* acc cnt)))))) The author doesn't take an idiomatic approach to programming in Clojure in most of his code snippets. [edit] Throwing java.lang.Exception if a condition is n…

> Throwing java.lang.Exception if a condition is not meat in your clojure functions? Don't do this either!!! What's the proper way of doing that in clojure ?

-way- is not the problem here. The java.lang.Exception is. :-) Throw specialized "Runtime Exceptions" would be the way to go. For example throw IllegalArgumentException runtime exception if function call receives inappropriate arguments.

You can also define your own specific (app-level) exception by proxying the RuntimeException or other relevant using the clojure's proxy macro.