+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 and/or the [OPAM](https://opam.ocaml.org) "package manager."
+These will make it easier to install additional add-ons further down the road.
+However, if you're not able to get them working, don't worry about it much.
+
+The current version of OCaml is 4.02.1 (released October 2014).
+<!-- 3.12.1 July 2011; 4.00.1 Oct 2012; 4.01.0 Sept 2013; 4.02.0 Aug 2014; 4.02.1 Oct 2014 -->
+
+
+* In your web browser:
+
+ There is a (slow, bare-bones) version of OCaml available for online use at <http://try.ocamlpro.com/>.
+
+
+* **To install in Windows**
+
+ There are *five* different strategies for installing OCaml on Windows. I don't know which works best.
+
+ 1. First, you can 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 an earlier
+ version of OCaml (4.01.0, from September 2013) is available.
+
+ 2. A second strategy uses a package called
+ [OCPWIN](http://ocaml.org/docs/install.html#OCPWINSelfContainedOCamlforWindows). This also installs only version 4.01.0.
+
+ 3. The [three remaining strategies](http://ocaml.org/docs/install.html#OCamlonCygwin) in some way
+ use the Cygwin environment, mentioned earlier on this page. At least one of
+ those three methods will automatically fetch and help you install Cygwin.
+ The first method listed on that page says it installs version 4.00.1, but
+ really it's been updated and now installs the (somewhat newer, but still
+ not the newest) version 4.01.0.
+
+ Some of these methods may automatically install Findlib for you. If not,
+ you can try installing it yourself but I think you'll need the Cygwin
+ system installed to do so. I'm not going 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 without MacPorts**
+
+ The people in charge of OCaml (they're at the French research institute INRIA) have stopped making pre-built packages for Mac OS X. One option you have is to use their package for a slightly older version of OCaml, 4.01.1 from Sept. 2013. You can find that as a "Precompiled binary for Mac OS X" on [this page](http://ocaml.org/releases/4.01.0.html). If, when you attempt to install this package, you get an error about its being from an "unidentified developer," you need to control-click on the `ocaml.pkg` file and select "Open", then when the warning box appears again, this time there will be an "Open" button that you can click. Then you can continue running the Installer.
+
+ A second option is to install the OPAM package manager and use that to build and install the latest version of OCaml. Here's how to do that:
+
+ 1. Download [this file](https://raw.github.com/ocaml/opam/master/shell/opam_installer.sh) and
+ note where it gets saved to. If it opens in your browser, then type
+ command-S / Save Page and save it somewhere on your disk, again noting its
+ location.
+
+ 2. Open a terminal and type:
+
+ sh /path/to/opam_installer.sh ~/bin
+
+ Except replace `/path/to` with the real location, that you noted in step 1. When prompted "Do you want OPAM to modify ~/.bash_profile and ~/.ocamlinit?", say "y".
+
+ 3. If that works, then type:
+
+ opam init --comp 4.01.0
+
+ or whatever it was that the OPAM installer prompted you to type. This will download and install a fresh version of OCaml, and will take a bit of time.
+
+<!-- To upgrade: opam switch 4.02.1 && eval `opam config env` -->
+
+<!--
+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:
+
+ ./configure
+ make package-macosx
+
+This will build an installer package which you should be able to
+double-click and install.
+-->
+
+* **To install on Mac with MacPorts**
+
+ You can install the current version of OCaml (4.02.1, from October 2014),
+ together with the Findlib add-on and OPAM package manager, by opening a Terminal and typing:
+
+ sudo port install ocaml ocaml-findlib opam
+
+ 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.
+
+* **To install on Linux**
+
+ Use your packaging system, for example, open a Terminal and
+ type:
+
+ sudo apt-get install ocaml opam camlp4-extra ocaml-findlib
+
+ That will install a version of OCaml and the Findlib add-on and OPAM package manager.
+
+ If you're using Ubuntu "Utopic" (14.10), there's [a note on the OPAM home page](https://opam.ocaml.org/doc/Install.html)
+ warning that its version of OPAM is broken, and not to use it. Here's how you can get (OCaml and) OPAM from a newer repository:
+
+ sudo apt-get install -y software-properties-common
+ sudo add-apt-repository -y ppa:avsm/ppa
+ sudo apt-get update
+ sudo apt-get install ocaml opam
+
+ If for some reason you can't get OCaml through your Linux 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-1.5.5.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:
+
+* 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 specific version of GHC, plus specific 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.
+
+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**:
+
+* 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.
+
+On **Mac without MacPorts**:
+
+* 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.
+
+<!--
+The Installer places everything in your system directories. If you'd like it instead in your user directory (easier to clean up later), you can do this after running the Installer: