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Comment by tibbon | Hacker News Reader

Is starting with Clojure a poor idea (jumping off the deep end)? I'm mainly a Ruby dev and looking to expand my knowledge-set

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There isn't really a great cost to learning the basics of a language. Lisp dialects are very easy to learn, at least to a beginner level. You can learn enough of any lisp dialect to start writing "useful" programs in a few days, just try them out in whatever order you prefer and see which one you like to get deeper into.

Depends on your environment. If you get Clojure set up with Light Table, it's pretty easy to mess with. I think Clojure is not as intuitive as Common Lisp or my brief explorations of Scheme.

If you want to know more about common lisp, I have a site for that: http://articulate-lisp.com

Clojure is a nice choice if you're looking to write production code, especially if you're already using other JVM languages (Java/Scala/JRuby/etc.)

However, Clojure strays from a number of standard common idioms in other Lisps, which, IMHO, makes Clojure a less-than-ideal candidate if you're looking to get the "full SICP" experience. It has a lot of other benefits as a language, but for a learning experience, you'll miss out on some of the idioms common to other Lisps.

But, give it a shot and see if it works for you. Once you've learned one, it's really to learn another dialect.

And, in the end, the only wrong answer to 'Which Lisp?' is the empty list[0]. :)

[0] This is an example of a super-nerdy Lisp joke which works in Common Lisp but not Clojure - in Common Lisp, 'nil', 'false', and the empty list are all the same value, (and all other values are considered "truthy"). In Clojure, they are three distinct entities, and there is a discrete "true" value.

The joke "My other car is a cdr" also works in Common Lisp and Scheme but not Clojure.

Wait, this one is news to me. How does Clojure break this? It still supports car/cdr, if I recall correctly, right?

The closest Clojure has to car/cdr is first/rest. It supports "cons" but only for creating sequences. Traditional Lisp car/cdr is one-location/other-location, and its cons puts together pairs of data. Often this is used for constructing sequences, but it is also often used for trees.

Clojure:

    user=> (cons 3 4)
    IllegalArgumentException Don't know how to create ISeq from: java.lang.Long  clojure.lang.RT.seqFrom (RT.java:494)

    user=> (cons 3 '(4))
    (3 4)

Common Lisp:

    CL-USER(1): (cons 3 4)

    (3 . 4)
    CL-USER(2): (cons 3 '(4))

    (3 4)
    CL-USER(3):

Yeah those error messages completely baffled me for the first few hours I spent in the Clojure REPL. It was strange enough to not have car/cdr and cons for working with tuples, but then I wrote a simple recursive algorithm and got a java.lang.StackOverflowError. I now understand why and the alternative idioms that Clojure provides, but at the time it was a WTF moment.

they are called first and rest in clojure, not car and CDR.

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