Real World Haskell

Chapter 23. GUI Programming with gtk2hs

Throughout this book, we have been developing simple text-based tools. While these are often ideal interfaces, sometimes a graphical user interface (GUI) is required. There are several GUI toolkits available for Haskell. In this chapter, we will look at one of them, gtk2hs.^[55]

Installing gtk2hs

Before we dive in to working with gtk2hs, you’ll need to get it installed. On most Linux, BSD, or other POSIX platforms, you will find ready-made gtk2hs packages. You will generally need to install the GTK+ development environment, Glade, and gtk2hs. The specifics of doing so vary by distribution.

Windows and Mac developers should consult the gtk2hs downloads site at http://www.haskell.org/gtk2hs/download/. Begin by downloading gtk2hs from there. Then you will also need Glade version 3. Mac developers can find this at http://www.macports.org/, while Windows developers should consult http://sourceforge.net/projects/gladewin32.

Overview of the GTK+ Stack

Before examining the code, let’s pause a brief moment and consider the architecture of the system we are going to use. First off, we have GTK+. GTK+ is a cross-platform GUI-building toolkit, implemented in C. It runs on Windows, Mac, Linux, BSDs, and more. It is also the toolkit beneath the GNOME desktop environment.

Next, we have Glade. Glade is a user-interface designer, which lets you graphically lay out your application’s windows and dialogs. Glade saves the interface in XML files, which your application ...