and that is what we recommend you use. If you're already using or comfortable with
another Scheme implementation, though, there's no compelling reason to switch.
- <!-- Racket doesn't have R7RS-small, and won't anytime soon. :-( Perhaps prefer Chicken? -->
+ Another good Scheme implementation is Chicken. For our purposes, this is in some
+respects superior to Racket, and in other respects inferior.
+<!--
+Racket doesn't have R7RS-small, and won't anytime soon. :-(
+Also Chicken's library collection seems stronger, or at least better organized and maintained.
+Other R7RS-friendly: [Gauche](http://practical-scheme.net/gauche), [Chibi](https://code.google.com/p/chibi-scheme).
+-->
- Racket stands to Scheme in something like the relation Firefox stands to HTML.
+ Racket and Chicken stand to Scheme in something like the relation Firefox stands to HTML.
- (Wikipedia on [Lisp](http://en.wikipedia.org/wiki/Lisp_%28programming_language%29),
+ (Wikipedia on
+[Lisp](http://en.wikipedia.org/wiki/Lisp_%28programming_language%29),
[Scheme](http://en.wikipedia.org/wiki/Scheme_%28programming_language%29),
-and [Racket](http://en.wikipedia.org/wiki/Racket_%28programming_language%29).)
+[Racket](http://en.wikipedia.org/wiki/Racket_%28programming_language%29), and
+and [Chicken](http://en.wikipedia.org/wiki/CHICKEN_%28Scheme_implementation%29).)
* **Caml** is one of two major dialects of *ML*, which is another large
family of programming languages. Caml has only one active "implementation",
more generally; but you can assume that what we're talking about always works more
specifically in OCaml.
- (Wikipedia on [ML](http://en.wikipedia.org/wiki/ML_%28programming_language%29),
+ (Wikipedia on
+[ML](http://en.wikipedia.org/wiki/ML_%28programming_language%29),
[Caml](http://en.wikipedia.org/wiki/Caml),
and [OCaml](http://en.wikipedia.org/wiki/OCaml).)
familiar with one of them, it's generally not hard to move between it and the
other.
- (Wikipedia on [Haskell](http://en.wikipedia.org/wiki/Haskell_%28programming_language%29).)
+ Like Scheme, Haskell has a couple of different implementations. The
+dominant one, and the one we recommend you install, is called GHC, short
+for "Glasgow Haskell Compiler".
+
+ (Wikipedia on
+[Haskell](http://en.wikipedia.org/wiki/Haskell_%28programming_language%29) and
+[GHC](https://en.wikipedia.org/wiki/Glasgow_Haskell_Compiler).)
<a name=installing></a>