## Identifying your system ##
We'll assume you're using either Mac OS X, or Windows, or Linux.
+If you're running **iOS**, you'll have a much harder time (perhaps impossible,
+perhaps not) getting this software to run on your machine, and we can't give
+you any guidance.
If you're using **Mac OS X**, take note of what version of the Mac OS you're
running. (Under the Apple Menu, select "About this Mac".)
* Mavericks (10.9)
* Yosemite (10.10)
-If you're running **iOS**, you probably can't use this software on that machine. (A bit more below.)
+Furthermore, Mac users will be in one of two subgroups:
-Furthermore, you'll be in one of two subgroups:
+* You'll have Apple's Xcode and the independent MacPorts system
+ installed. (Probably you don't. If you don't know what I'm talking about, you don't have these.)
-* You'll have Apple's Xcode and the independent MacPorts system
- installed. (Probably you don't. If you don't know what I'm talking about, you don't have these.)
+ If you don't have these, but want to try this route, you can read about
+ the MacPorts system at <http://www.macports.org/>.
+ This automates the building of Unix-type software on your Mac; it
+ makes it a lot easier to check for dependencies, use more-recent
+ versions of things, and so on. (Though as it happens, MacPorts only has an older version of
+ our chosen implementation of Scheme.)
- If you don't have these, but want to try this route, you can read about
- the MacPorts system at <http://www.macports.org/>.
- This automates the building of Unix-type software on your Mac; it
- makes it a lot easier to check for dependencies, use more-recent
- versions of things, and so on. (Though as it happens, MacPorts only has an older version of
- our chosen implementation of Scheme.)
+ There are also other package management systems available for the Mac, notably Homebrew and Fink. I only know a little bit about them.
- Xcode is available at
- <http://developer.apple.com/technologies/tools/xcode.html>. Some
- versions of this have been available for free, though you do have to
- register with Apple as an "Apple Developer", which involves accepting a
- legal agreement with Apple. I have an older version of this installed.
- If you download a recent version, email me and let me know how the
- process works so I can tell others. There are instructions about how to
- get Xcode in the MacPorts installation guide.
- <!--
- The latest version of Xcode to work with Leopard is 3.14; more
- recent versions (>= 3.2) require Snow Leopard. 3.2.6 is last version that can be downloaded for free by users of 10.6 / Snow Leopard. (But if they pay, they can use up to Xcode 4.2.)
- Xcode 4.1 was free to all users of 10.7 / Lion. Is Xcode 4.6.x still available for free? Are Xcode 5.x and/or 6.x available for free?
- -->
+ There are instructions about how to get Xcode on the [Installing MacPorts](https://www.macports.org/install.php) page.
+ Some versions of [Xcode](http://developer.apple.com/xcode.html) are available for free on the Mac App Store.
+ Other versions are available through Apple's Developer website (some of these are free, but do require you to
+ register with Apple as an "Apple Developer", which involves clicking to accept a legal agreement with Apple).
+ I have an older version of this installed. If you download a recent version, email me and let me know how the
+ process works so I can tell others.
+ <!--
+ The latest version of Xcode to work with 10.5 / Leopard is 3.14; more recent versions (>= 3.2) require 10.6 / Snow Leopard.
+ 3.2.6 is last version that can be downloaded for free by users of 10.6 / Snow Leopard. (But if they pay, they can use up to Xcode 4.2.)
+ Xcode 4.1 was free to all users of 10.7 / Lion. Is Xcode 4.6.x still available for free? Are Xcode 5.x and/or 6.x available for free?
+ -->
+* Or you won't have those installed. (**Most Mac users will be in this group.**)
+ Then you'll need pre-packaged (and usually pretty GUI) installers for
+ everything. These are great when they're available and kept up-to-date;
+ however sometimes those conditions aren't met.
-* Or you won't have those installed. (**Most Mac users will be in this group.**)
- Then you'll need pre-packaged (and usually pretty GUI) installers for
- everything. These are great when they're available and kept up-to-date;
- however sometimes those conditions aren't met.
If you're using **Windows**, you'll be in one of two subgroups:
-* You'll have the Cygwin system
- <http://www.cygwin.com/> installed.
- This puts a Unix-like layer on top of your Windows system,
- and makes it easier for you to use the same software everybody
- else will be using, without its needing as much special-for-Windows
- treatment. However, many of you won't have this installed.
+* You'll have the Cygwin system <http://www.cygwin.com/> installed.
+ This puts a Unix-like layer on top of your Windows system,
+ and makes it easier for you to use the same software everybody
+ else will be using, without its needing as much special-for-Windows
+ treatment. However, many of you won't have this installed.
+
+* You won't have Cygwin installed. (**Most Windows users will be in this group.**)
+ You might in theory have a different group of compilers installed
+ (MinGW, or Microsoft Visual C++) but we'll assume that the overwhelming
+ majority of users in this group don't have access to a compiler and
+ need pre-packaged installers for everything.
-* You won't have Cygwin installed. You might in theory have
- a different group of compilers installed (Microsoft Visual C++) but
- we'll assume that the overwhelming majority of users in this group
- don't have access to a compiler and need pre-packaged installers
- for everything.
If you're using **Linux**, you could be using any one of numerous packaging
systems.
-* We'll give examples using the packaging system shared by Debian and Ubuntu,
- and we'll assume that those of you using different packaging systems will know
- how to make the relevant substitutions. You may also want to take note of the
- output of the "uname -srm" command. On my machine this tells me "Linux
- 3.12.8-extrastuff x86\_64". That tells me I'm running the x86\_64 (as opposed to the
- i686 or i386 or whatever) version of Linux, and that I'm running kernel
- version 3.12.8.
-
-**For all of these groups**, a general item to take note of is what "processor architecture" your machine is running. Three of the possibilities are:
-
-* One of Intel's i386, i486, i586, i686 architectures. These are collectively known as "x86" or "IA-32" or sometimes just "32-bit".
-* Intel or AMD's x86\_64 architecture. This is sometimes also called "x64" or "amd64" or "IA-64" or sometimes just "64-bit".
-* ARM or some other architecture. These are generally lower-powered machines, like iPads. Some of the software we're proposing *might* in principle be capable of running on such machines, but installers don't seem to be available. We'll assume you have access to an x86 or x86\_64 machine.
-
-In the Linux example above, I could tell my machine is running x86 because the
-result of the `uname` command said "i386" at the end. Another machine I have
-says "x86\_64" at the end. On a Mac, you can also say `uname -m` in a Terminal
-session, and it will say something like "i386". I think that Mac OS's from Lion
-/ 10.7 forward have all been x86\_64-only. On Windows, I don't know how to
-collect this information. But generally, machines running Windows XP will
-probably be i386/32-bit (unless it's a version of Windows with "64-bit" or
-"x64" in its title); machines running Windows Vista or Windows 7 or Windows 8
-could be running either x86/32-bit or x64/64-bit.
-(Update: I found
-[this Microsoft page](http://windows.microsoft.com/en-us/windows/32-bit-and-64-bit-windows)
-that may help.)
+* We'll give examples using the packaging system shared by Debian and Ubuntu,
+ and we'll assume that those of you using different packaging systems will know
+ how to make the relevant substitutions.
+
+
+**For everyone**, a general item to take note of is what "processor architecture" your machine is running. Three of the possibilities are:
+
+* One of Intel's i386, i486, i586, i686 architectures. These are collectively known as "x86" or "IA-32" or sometimes just "32-bit".
+* Intel or AMD's x86\_64 architecture. This is also called "x64" or "amd64" or "IA-64" or sometimes just "64-bit". (Note that these *aren't* "x86" machines, even though "x86\_64" starts with those letters.)
+* ARM or some other architecture. These are generally lower-powered machines, like iPads. Some of the software we're proposing *might* in principle be capable of running on such machines, but installers don't seem to be available. We'll assume you have access to an x86 or x86\_64 machine.
+
+On Linux or Mac OS X, you can open a terminal and type `uname -m`. If the
+result is "x86\_64", then you've got x64/64-bit. If it's "i386" or something
+like that, then you've got x86/32-bit. I think that Mac OS Xs from 10.7 / Lion
+forward have all been x86\_64-only.
+
+On Windows,
+[here is a page that can help you figure this out](http://windows.microsoft.com/en-us/windows/32-bit-and-64-bit-windows).
+I think that most machines running Windows XP will be x86/32-bit (unless it's
+a version of Windows with "64-bit" or "x64" in its title); machines running
+Windows Vista or Windows 7 or Windows 8 could be running either x86/32-bit or
+x64/64-bit.
## PLEASE REPORT PROBLEMS (AND SOLUTIONS!) ##
## Getting Scheme ##
-**Scheme** is one of two major dialects of *Lisp*, which is a large family of
-programming languages. The other dialect is called "Common Lisp." Scheme is the
-more clean and minimalistic dialect, and is what's mostly used in academic
-circles.
+**Scheme** is one of two or three major dialects of *Lisp*, which is a large family
+of programming languages. The other dialects are called "Common Lisp" and "Clojure".
+Scheme is the more clean and minimalist dialect, and is what's mostly used in
+academic circles.
+
+* In your web browser:
+
+ There is a (slow, bare-bones) version of Scheme available for online use at <http://tryscheme.sourceforge.net/>.
Scheme itself has umpteen different "implementations", which share most of
their fundamentals, but have slightly different extensions and interact with
-the operating system differently. One major implementation used to be called
-PLT Scheme, but then a few years ago changed their name to Racket.
-This 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.)
+the operating system differently. One major implementation is called [Racket](http://racket-lang.org),
+and that is what we recommend you use. (A few years back they were called PLT Scheme, but then
+they changed their name to Racket.)
+If you're already using or comfortable with
+another Scheme implementation, though, there's no compelling reason to switch.
+
+
+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.
+
+<!--
+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 stands to Scheme in something like the relation Firefox stands to HTML. It's one program among others for working with the language; and many of those programs (or web browsers) permit different extensions, have small variations, and so on.
+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.
Racket has several components. The two most visible components for us are a command-line interpreter named "racket" and a teaching-friendly editor/front-end named "DrRacket". You will probably be working primarily or wholly in the latter.
+<!-- "racket" used to be mzscheme, "DrRacket" used to be DrScheme -->
-<!-- racket used to be mzscheme, DrRacket used to be DrScheme -->
+The current version of Racket is 6.1.1 (released November 2014).
-* In your web browser:
+* **To install in Windows**
- There is a (slow, bare-bones) version of Scheme available for online use at <http://tryscheme.sourceforge.net/>.
+ Go to <http://racket-lang.org/download/>. Download and install the "Windows x64" version. (Or the "Windows x86" verson if you have an older, 32-bit system.)
+* **To install on Mac without MacPorts**
-* **To install in Windows**
+ Go to <http://racket-lang.org/download/>. Download and install the option for your system, most likely "Macintosh
+ OS X (Intel 64-bit)".
- Go to <http://racket-lang.org/download/>. Download and install the "Windows x64" version. (Or the "Windows x86" verson if you have an older, 32-bit system.)
+ After you copy the files from the Installation disk to your /Applications folder, I think it's helpful to do these additional steps. In a Terminal, type:
-* **To install on Mac without MacPorts**
+ sudo ln -s /Applications/Racket*/DrRacket.app /Applications/
+ sudo ln -s /Applications/Racket*/bin/racket /usr/bin/
- Go to <http://racket-lang.org/download/>. Download and install the option for your system, most likely "Macintosh
- OS X (Intel 64-bit)".
+ Then you can launch Racket either by double-clicking the DrRacket icon in
+ your Applications folder (this gives you the GUI interface); or by typing
+ `racket` in a Terminal (this gives you the command-line version).
-* **To install on Mac with MacPorts**
+* **To instead install Chicken Scheme on Mac without MacPorts**
- You can install a command-line version of
- PLT Scheme (dating from early 2009) by opening a Terminal
- and typing:
+ 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.
- sudo port install mzscheme
+ 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.
+ 3. Type `less README` and read that file.
+ 4. Type `sudo mkdir -p /usr/local`
+ 5. Type `make PLATFORM=macosx XCODE_DEVELOPER= XCODE_TOOL_PATH=/usr/bin`
- If you want the GUI components, I think you'll need to use the
- "Mac/without MacPorts" installation options above.
+ 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:
- I recommend also typing:
+ 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.
+ 8. At this point you can type `which chicken`. If it gives you an answer of "/usr/local/bin/chicken", then skip to the next step. Else you should type `echo 'export PATH=/usr/local/bin:$PATH' >> ~/.bashrc`, then exit and restart your Terminal session.
+ 9. In your terminal, type `chicken-install -sudo r7rs datatype matchable monad`. This will download, build, and install a few extensions (Chicken calls them "eggs") relevant to ideas we'll be working with in this course.
- sudo port install rlwrap
+* **To install on Mac with MacPorts**
- then if you ever use the command-line program `mzscheme` (or `racket`), you should start it by typing `rlwrap mzscheme`. This gives
- you a nice history of the commands you've already typed, which you can scroll up and down in with your
- keyboard arrows.
+ Unfortunately, MacPorts doesn't have Racket itself available. It only has an older version from when they still called
+ themselves PLT Scheme. And even then, it only has the command-line program "mzscheme" (what's nowadays called "racket"); it
+ doesn't have the GUI program that corresponds to what's now called "DrRacket". You can install mzscheme by opening a Terminal
+ window and typing:
-* **To install on Linux**
+ sudo port install mzscheme
- Use your packaging system, for example, open a Terminal and
- type:
+ <!-- mzscheme v4.1.5, from March 2009; latest mzscheme is 4.2.5, from April 2010 -->
- sudo apt-get install racket
+ If you want the GUI components, I think you'll need to use the
+ "Mac/without MacPorts" installation options above. Or you could try the Chicken Scheme implementation instead of Racket. This is more current.
+ To do that, type:
- It's very likely that your packaging system has some version of
- Racket available, so look for it. However, if you can't find it you
- can also install a pre-packaged binary from the Racket website at <http://racket-lang.org/download/>.
- Choose the option for your version of Linux (Ubuntu and Debian are available).
+ sudo port install chicken readline
- As above, I recommend you also type:
+ <!-- chicken v4.8.0.2, from Feb 2013; latest available is 4.9.0.1, from Nov 2014 -->
- sudo apt-get rlwrap
+ Whether you use mzscheme or Chicken, I recommend also typing:
- then if you ever use the command-line program `mzscheme` (or `racket`), you should start it by typing `rlwrap mzscheme`. This gives
- you a nice history of the commands you've already typed, which you can scroll up and down in with your
- keyboard arrows.
+ sudo port install rlwrap
+
+ then if you ever use the command-line program `mzscheme` (or `racket`, for that matter), you should start it by typing `rlwrap mzscheme` (or whatever). This gives
+ you a nice history of the commands you've already typed, which you can scroll up and down in with your
+ keyboard arrows.
+
+* **To install on Linux**
+
+ Use your packaging system, for example, open a Terminal and
+ type:
+
+ sudo apt-get install racket
+
+ It's very likely that your packaging system has some version of
+ Racket available, so look for it. However, if you can't find it you
+ can also install a pre-packaged binary from the Racket website at <http://racket-lang.org/download/>.
+ Choose the option for your version of Linux (Ubuntu and Debian are available).
+
+ As above, I recommend you also type:
+
+ sudo apt-get rlwrap
+
+ then if you ever use the command-line program `mzscheme` (or `racket`), you should start it by typing `rlwrap mzscheme` (or whatever). This gives
+ you a nice history of the commands you've already typed, which you can scroll up and down in with your
+ keyboard arrows.
## Getting OCaml ##
programming languages. The other dialect is called "SML" and has several
implementations. But Caml has only one active implementation, OCaml or
Objective Caml, developed by the INRIA academic group in France.
-
-
-*Will add more information about this soon.*
-
-<!--
+Sometimes we may refer to Caml or ML
+more generally; but you can assume that what we're talking about always works more
+specifically in OCaml.
It's helpful if in addition to OCaml you also install the Findlib add-on.
This will make it easier to install additional add-ons further down the road.
However, if you're not able to get that working, don't worry about it much.
+The current version of OCaml is 4.02.1 (released October 2014).
-* **To install in Windows**
+* *Another instruction page focuses on [OPAM](http://ocaml.org/docs/install.html), also [this](https://opam.ocaml.org).*
- Go to <http://caml.inria.fr/download.en.html>.
- You can probably download and install the
- "Self installer for the port based on the MinGW toolchain"
- even if you don't know what MinGW or Cygwin are.
- Some features of this require Cygwin, but it looks like
- it should mostly work even for users without Cygwin.
- At the time of this writing, only an installer for the previous
- version of OCaml (3.11.0, from January 2010) is available.
+* *[More details about installing OCaml on Macs, if needed](http://cocan.org/getting_started_with_ocaml_on_mac_os_x)*
- To install the Findlib add-on, you must have the
- Cygwin system installed. We assume few of you do,
- so we're not going to try to explain how to do this.
- If you want to figure it out yourself, go to the
- Findlib website at <http://projects.camlcity.org/projects/findlib.html>.
+* In your web browser:
-* **To install on Mac without MacPorts**
+ There is a (slow, bare-bones) version of OCaml available for online use at <http://try.ocamlpro.com/>.
- To install OCaml 3.12 (just released this summer), go to
- <http://caml.inria.fr/download.en.html>
- and download and install the "Binary distribution for Mac OS X"
- To install the Findlib add-on, you'll need the Xcode development tools
- to compile it yourself. Once you get that far, it's probably easiest
- for you to install MacPorts and just install things using the MacPorts
- instructions. (Use the MacPorts version of OCaml, instead of installing
- the package from the caml.inria.fr website, as described above)
- However, if you do have Xcode, and want to do without MacPorts, then
- what you need to do is download Findlib from
- <http://download.camlcity.org/download/findlib-1.2.6.tar.gz>.
- Unpack the download, open a Terminal and go into the folder you just
- unpacked, and type:
+* **To install in Windows**
- ./configure
- make package-macosx
+ Go to <http://caml.inria.fr/download.en.html>.
+ You can probably download and install the
+ "Self installer for the port based on the MinGW toolchain"
+ even if you don't know what MinGW or Cygwin are.
+ Some features of this require Cygwin, but it looks like
+ it should mostly work even for users without Cygwin.
+ At the time of this writing, only an installer for the previous
+ version of OCaml (3.11.0, from January 2010) is available.
- This will build an installer package which you should be able to
- double-click and install.
+ To install the Findlib add-on, you must have the
+ Cygwin system installed. We assume few of you do,
+ so we're not going to try to explain how to do this.
+ If you want to figure it out yourself, go to the
+ Findlib website at <http://projects.camlcity.org/projects/findlib.html>.
-* **To install on Mac with MacPorts**
+* **To install on Mac without MacPorts**
- You can install the previous version of OCaml (3.11.2,
- from January 2010), together with the Findlib add-on, by opening a Terminal
- and typing:
+ To install OCaml 3.12 (just released this summer), go to
+ <http://caml.inria.fr/download.en.html>
+ and download and install the "Binary distribution for Mac OS X"
- sudo port install ocaml caml-findlib
+ To install the Findlib add-on, you'll need the Xcode development tools
+ to compile it yourself. Once you get that far, it's probably easiest
+ for you to install MacPorts and just install things using the MacPorts
+ instructions. (Use the MacPorts version of OCaml, instead of installing
+ the package from the caml.inria.fr website, as described above)
+ However, if you do have Xcode, and want to do without MacPorts, then
+ what you need to do is download Findlib from
+ <http://download.camlcity.org/download/findlib-1.2.6.tar.gz>.
+ Unpack the download, open a Terminal and go into the folder you just
+ unpacked, and type:
- As with Scheme, it's helpful to also have rlwrap installed, and to start OCaml as `rlwrap ocaml`. This gives
- you a nice history of the commands you've already typed, which you can scroll up and down in with your
- keyboard arrows.
-
+ ./configure
+ make package-macosx
-* [More details about installing OCaml on Macs, if needed](http://cocan.org/getting_started_with_ocaml_on_mac_os_x)
+ This will build an installer package which you should be able to
+ double-click and install.
-* **To install on Linux**
+* **To install on Mac with MacPorts**
- Use your packaging system, for example, open a Terminal and
- type:
+ You can install the previous version of OCaml (3.11.2,
+ from January 2010), together with the Findlib add-on, by opening a Terminal
+ and typing:
- sudo apt-get install ocaml ocaml-findlib
+ sudo port install ocaml caml-findlib
- That will install a version of OCaml (probably 3.11.2, from January 2010)
- and the Findlib add-on.
+ As with Scheme, it's helpful to also have rlwrap installed, and to start OCaml as `rlwrap ocaml`. This gives
+ you a nice history of the commands you've already typed, which you can scroll up and down in with your
+ keyboard arrows.
- If for some reason you can't get OCaml through your
- packaging system, you can go to
- <http://caml.inria.fr/download.en.html>.
- Pre-packaged binary installers are available for several Linux systems.
+* **To install on Linux**
- If you can't get findlib through your packaging system, you'll
- need to download it from
- <http://download.camlcity.org/download/findlib-1.2.6.tar.gz>.
- and use gcc to compile it yourself. If you don't know how to
- do that, you probably don't want to attempt this.
- Here are the INSTALL notes:
- <https://godirepo.camlcity.org/svn/lib-findlib/trunk/INSTALL>.
+ Use your packaging system, for example, open a Terminal and
+ type:
- As with Scheme, it's helpful to also have rlwrap installed, and to start OCaml as `rlwrap ocaml`. This gives
- you a nice history of the commands you've already typed, which you can scroll up and down in with your
- keyboard arrows.
+ sudo apt-get install ocaml ocaml-findlib
+
+ That will install a version of OCaml and the Findlib add-on.
+
+ If for some reason you can't get OCaml through your
+ packaging system, you can go to
+ <http://caml.inria.fr/download.en.html>.
+ Pre-packaged binary installers are available for several Linux systems.
+
+ If you can't get findlib through your packaging system, you'll
+ need to download it from
+ <http://download.camlcity.org/download/findlib-1.2.6.tar.gz>.
+ and use gcc to compile it yourself. If you don't know how to
+ do that, you probably don't want to attempt this.
+ Here are the INSTALL notes:
+ <https://godirepo.camlcity.org/svn/lib-findlib/trunk/INSTALL>.
+
+ As with Scheme, it's helpful to also have rlwrap installed, and to start OCaml as `rlwrap ocaml`. This gives
+ you a nice history of the commands you've already typed, which you can scroll up and down in with your
+ keyboard arrows.
+
+
+## Getting Haskell ##
+
+This last installation is less crucial than the others, since we will be focusing
+primarily on Scheme and OCaml. However we, and the readings you come across,
+will sometimes mention Haskell, so it might be worth your installing this too,
+so that you have it available to play around with.
+
+Haskell is used a lot in the academic contexts we'll be working through. At one point, Scheme
+dominated these discussions but now Haskell seems to do that.
+
+Haskell's surface syntax differs from Caml, and there are various important things one can do in
+each of Haskell and Caml that one can't (or can't as easily) do in the
+other. But these languages also have *a lot* in common, and if you're
+familiar with one of them, it's generally not hard to move between it and the
+other.
+
+* In your web browser:
+
+ There is a (slow, bare-bones) version of Haskell available for online use at <http://tryhaskell.org/>.
+
+Like Scheme, Haskell has a couple of different implementations. The dominant one, and the one we recommend you install, is called [GHC](https://wiki.haskell.org/GHC), short for "Glasgow Haskell Compiler". To install this on your machine, there are a couple of different strategies. It's helpful to understand some lingo as you begin this process:
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+* As mentioned, **GHC** is the main Haskell engine or compiler you'll be installing. The current version is 7.8.4, from December 2014.
+* **gcc** and **llvm/clang** and **Xcode** and **MinGW** are names for other compilers on various systems. Oftentimes these will be used during the installation process to get GHC up and running. Some of the strategies described below will help you install these if they're not already on your machine.
+* **alex** and **happy** and **haddock** are names of various Haskell helper programs that GHC uses to get up and running.
+* **[Cabal](https://www.haskell.org/cabal)** is a "package manager" for Haskell. It allows you to install libraries or extensions that other people have built. (Usually those are published at the [Hackage](https://hackage.haskell.org) web site.) Some of these are experimental and may not always work; others are quite fundamental and are almost de facto parts of what people expect in a Haskell system.
+* **[Haskell Platform](https://www.haskell.org/platform)** is a standard bundle that includes a fixed version of GHC, plus fixed versions of some of the most popular libraries or extensions. This is updated once or twice a year. The current version is 2014.2.0.0, from August 2014. It includes GHC version 7.8.3.
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+The easiest way to get up and running with Haskell/GHC is to install the Haskell Platform. Here's how to do that **on Windows**:
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+* Go to <https://www.haskell.org/platform/windows.html> and follow the instructions. It looks like this process will automatically install the MinGW compiler needed to get this build of Haskell running on Windows.
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+On **Mac without MacPorts**:
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+* Go to <https://www.haskell.org/platform/mac.html> and follow the instructions. This requires Mac OS X 10.6 / Snow Leopard or later; but there is a link to an earlier version of Haskell Platform, that's built for Mac OS X 10.5 / Leopard. During the installation, you may be prompted to install "the command line developer tools"; this is a portion of what Apple bundles together with Xcode (mentioned above on this page). The installer will take care of getting these for you if you give it permission.
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+On **Mac with MacPorts**:
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+* In a Terminal, type `sudo port install haskell-platform`.
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+On **Ubuntu or Debian Linux**:
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+* In a Terminal, type `sudo apt-get install haskell-platform`.
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+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.
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+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.
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