Differences between #lang scheme and #lang racket

I'm guessing that #lang racket is a dialect of scheme with much more out of the box structures and common functions and perhaps would be more pedagogic. What are the perks a #lang racket against #lang scheme?

Is it best (or even possible) to use #lang scheme in racket to follow all the content of 'Structure and Interpretation of Computer Programs' or even 'How to Design Programs'. HtDP is #lang racket specific?

Whatever code written in #lang scheme, as long as libraries are not being included, can be used in 开发者_如何学Cchicken scheme or any main interpreter?

Thanks in advance.

1. Yes, #lang racket is the racket default dialect, with lots of extensions.

2. Two places where it is not an extension: if must have an else branch, and pairs are immutable (no set-car! and set-cdr!).

3. #lang scheme was used for a while before the name change, and now #lang racket is used consistently. But we kept #lang scheme around for compatibility (as well as various scheme/--- libraries that are kept and can sometime be different than racket/--- counterparts). There's no reason to use #lang scheme in new code.

4. To follow SICP, don't use any of these -- there's a SICP language available (usable with #lang sicp), originally written by Neil Van Dyke, but now maintained within the Racket community.

5. To follow HtDP, don't use any of these, use the student languages. There are also new #lang-based variants like #lang htdp/bsl but they're not in a complete shape, yet. (And HtDP is not #lang racket specific.)

6. No, Racket is very different from Chicken Scheme. You might be able to run some code in both, but those would probably be only tiny toy examples.