PLT Scheme is a Racket | Hacker News Reader

PLT Scheme is a Racket

racket-lang.org

42 pointssenki22 comments

In my experience, recursion is the hard part of teaching a functional language like Sch^H^H^H Racket.

I've often wondered if purpose-building a tool for visualizing recursive processes would help.

They could call it Ponzi.

I learned recursion in C. Visualizing the stack, which was encouraged for whatever reason in the books I was reading, was useful to me.

In a Ponzi Scheme, one concentrates on the stock, rather than the stack, I think... ;)

What books were those? Sounds useful, I'd like to read that too.

Programming Abstractions in C: http://www.amazon.com/Programming-Abstractions-Second-Comput...

there might have been others but that was the main one where afterward recursion no longer confused or scared me.

there may be other books that are far more suitable. i would be surprised if there weren't, even. but that's the one i used.

I checked the author, Eric Roberts, and it looks like recursion is his specialty. Good reference, thanks for the link!

http://www.amazon.com/Eric-Roberts/e/B001IOH3DO/ref=ntt_athr...

> In my experience, recursion is the hard part ...

My limited experience has been different. I've been trying to make time to learn Scheme lately, and recursion seems simple enough. You can just practice it until it makes sense. What I find difficult is understanding what symbols are and what single-quoting actually means. No Scheme book I've seen yet just comes out and actually tells you in plain language what a symbol is.

Single quoting lets you pass a list without evaluating it.

(car (eval '(a b c))) vs. (car (a b c))

Do the same thing.

Have you read SICP? Somewhere in the 1st-3rd chapter there's an explanation of first-order evaluation that scheme uses. Once you know how scheme evals sexps, it makes sense that quote skips some of the steps of evaluation. I strongly recommend the SICP/Little Schemer/Seasoned Schemer if you haven't heard of them.

Don't macros change the rule a bit?

> Have you read SICP?

I'm still in chapter 1.

Thanks for the explanation of the single quote. Can I convince you to add something about what a "symbol" is (and if it's connected in some way to the single-quote mechanism)?

Perhaps this can help: http://scheme.com/tspl4/objects.html#./objects:h11

Thank you.

The new website is not complete yet; more info on the changes: http://www.racket-lang.org/new-name.html

Probably the first thing you want to do is put whatever is supposed to be on http://docs.racket-lang.org up because that's resulting in lots of broken links on the front page.

I think it would be appropriate to post again when the site is complete.

How is this change going to be implemented in Linux repositories?

I installed the old busted PLT/DrScheme via repo, will it get automatically updated to the new hotness Racket, or will I need to keep an eye out for a new package?

That's up to the linux packagers. It took them a while to settle on "plt-scheme" in the past, so it will probably take some time now too.

Since the documentation is'nt working, here's one question - is there anything similar to Leiningen for Clojure or , to a lesser extent, SBT for scala ?

I've thought about the same thing... it would be really nice to have something like this for Clojure...

We used Dr. Scheme through a lot of my college courses and it helped out

Cool -- have you told Robby about it? Do you envision this being a teaching language or production?

This is not my little project, it's a re-branding of the good old PLT Scheme by the original team. I just post the news. :O

As far as I know only the names changes.

There's also a release of version 5.0.0.1

5.0.0.1 is the version of the repository -- it's a development version that should not be considered stable.

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