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](http://www.call-cc.org). For our purposes, this is in some respects
superior to Racket, and in other respects inferior. If you have any issues with installing or using Racket, you could
try this out instead. You might even want to install both.
<!--
-[Gauche](http://practical-scheme.net/gauche),
-or [Chibi](https://code.google.com/p/chibi-scheme). The later in that list you go, the more likely it
-is that you'll have to compile the software yourself. (Thus Mac users will need Xcode; if you try installing the Haskell Platform, described further down this page, first, that should take care of automatically getting the pieces of Xcode you need. Then you can come back and finish installing Scheme.)
+Racket doesn't have R7RS-small, and won't anytime soon.
+Other R7RS-friendly: [Gauche](http://practical-scheme.net/gauche), [Chibi](https://code.google.com/p/chibi-scheme).
-->
Racket and Chicken stand to Scheme in something like the relation Firefox stands to HTML. They are two programs (or platforms) among others for working with the Scheme language; and many of those programs (or web browsers) permit different extensions, have small variations, and so on.
* **To instead install Chicken Scheme on Mac without MacPorts**
- Here are the exact steps I just verified worked. Note that I installed the Haskell Platform, described further down this page, first; that installed some developer tools that were needed to build and install Chicken.
+ Here are the exact steps I just verified worked. Note that I *first installed the Haskell Platform*, described further down this page; that installed some developer tools that were needed to build and install Chicken. If you don't know how to open a Terminal, move between directories, copy / rename / delete files and so on, then you're probably best off not doing this. You could break something.
1. Go to <http://code.call-cc.org>, and click the "Source code" link near the top. Current version is 4.9.0.1, released November 2014. This should fetch a file to your download folder, and will probably automatically unpack that file into a folder, "chicken-4.9.0.1". Click on that folder and press command-C / Copy, then open a Terminal.
2. In the terminal type `cd` followed by a space, then press command-V / Paste. Then press enter. This will move your session into the folder you just downloaded.
4. Type `sudo mkdir -p /usr/local`
5. Type `make PLATFORM=macosx XCODE_DEVELOPER= XCODE_TOOL_PATH=/usr/bin`
- The options starting with `XCODE_` are to tell the Chicken build scripts that I've got the developer tools installed in my main system, rather than as part of Xcode. (That's where the Haskell Platform installer put them.)
+ The options starting with `XCODE_` are to tell the Chicken build scripts that I've got the developer tools installed in my main system, rather than as part of Xcode. (That's where the Haskell Platform installer put them.) Continuing:
6. Wait a while while Chicken builds.
7. If it finishes with no errors, then type `sudo make PLATFORM=macosx XCODE_TOOL_PATH=/usr/bin install`. This will prompt you for your account password, and then install Chicken underneath your `/usr/local` directory.
* In a Terminal, type `sudo apt-get install haskell-platform`.
----
+If any of the instructions above don't work, then you can try alternative instructions for [Windows](http://new-www.haskell.org/downloads/windows) or [Mac](http://new-www.haskell.org/downloads/osx) or [Ubuntu](http://new-www.haskell.org/downloads/linux). After installing the software, you should open a terminal and type `cabal update && cabal install alex happy`. If typing `which ghci` in a Terminal doesn't give you any reply, you may need to type `echo 'export PATH=/usr/local/bin:$PATH' >> ~/.bashrc`, then exit and restart your Terminal session.
-* [Here is more info](https://github.com/pittsburgh-haskell/haskell-installation) about installing Haskell.
-
-
-* It's useful to know about the general [Haskell wiki](https://wiki.haskell.org) (not restricted to just GHC). They have a [Getting Started](https://wiki.haskell.org/Haskell_in_5_steps) page, which also recommends that you install the Haskell Platform.
-
-* <http://new-www.haskell.org/downloads>
+It's useful to know about the general [Haskell wiki](https://wiki.haskell.org) (not restricted to just GHC). They have a [Getting Started](https://wiki.haskell.org/Haskell_in_5_steps) page, which also recommends that you install the Haskell Platform.