Generate Haskell bindings for GObject Introspection capable libraries.
To compile the bindings generated by haskell-gi
, make sure that you have installed the necessary development packages for the libraries you are interested in. The following are examples for some common distributions. (If your distribution is not listed please send a pull request!)
sudo dnf install gobject-introspection-devel webkitgtk4-devel gtksourceview3-devel
sudo apt-get install libgirepository1.0-dev libwebkit2gtk-4.0-dev libgtksourceview-3.0-dev
sudo pacman -S gobject-introspection gobject-introspection-runtime gtksourceview3 webkit2gtk
Install Homebrew and install GTK and GObject Introspection:
brew install gobject-introspection gtk4
Ensure the path to libffi (probably /usr/local/opt/libffi/lib/pkgconfig
) is in the PKG_CONFIG_PATH environment variable.
Please see here for detailed installation instructions in Windows.
The most recent versions of the generated bindings are available from hackage. To install, start by making sure that you have a recent (2.0 or later) version of cabal-install
, for instance:
$ cabal install cabal-install
$ cabal --version
cabal-install version 2.4.1.0
compiled using version 2.4.1.0 of the Cabal library
Here is an example "Hello World" program:
{-# LANGUAGE OverloadedStrings, OverloadedLabels, OverloadedRecordDot, ImplicitParams #-}
{- cabal:
build-depends: base >= 4.16, haskell-gi-base, gi-gtk == 4.0.*
-}
import Control.Monad (void)
import qualified GI.Gtk as Gtk
import Data.GI.Base
activate :: Gtk.Application -> IO ()
activate app = do
button <- new Gtk.Button [#label := "Click me",
On #clicked (?self `set` [#sensitive := False,
#label := "Thanks for clicking me"])]
window <- new Gtk.ApplicationWindow [#application := app,
#title := "Hi there",
#child := button]
window.show
main :: IO ()
main = do
app <- new Gtk.Application [#applicationId := "haskell-gi.example",
On #activate (activate ?self)]
void $ app.run Nothing
This program uses the new OverloadedRecordDot
extension in GHC 9.2, so make sure you have a recent enough version of GHC installed. To run this program, copy it to a file (hello.hs
, say), and then
$ cabal run hello.hs
For a more involved example, see for instance this WebKit example. Further documentation can be found in the Wiki.
The translation from the original C API to haskell-gi is fairly
straightforward: for method names simply remove the library prefix
(gtk
, gdk
, etc.), and convert to camelCase. I.e. gtk_widget_show
becomes
widgetShow
in the module GI.Gtk
(provided by the gi-gtk
package).
For properties, add the type of the object as a prefix: so the sensitive
property of GtkWidget
becomes widgetSensitive
in gi-gtk
. These can be set using the new
syntax, as follows:
b <- new Button [widgetSensitive := True]
or using set
after having created the button
b `set` [widgetSensitive := False]
Alternatively you can use setWidgetSensitive
and friends to set properties individually if you don't like the list syntax.
Finally, for signals you want to use the onTypeSignalName
functions, for example onButtonClicked
:
onButtonClicked b $ do ...
This is the basic dictionary. Note that all the resulting symbols can be conveniently searched in hoogle.
There is also support for the OverloadedLabels
extension in GHC 8.0 or higher. So the examples above can be shortened (by omitting the type that introduces the signal/property/method) to
b <- new Button [#sensitive := True]
on b #clicked $ do ...
#show b
Hopefully this helps to get started! For any further questions there is a gitter channel that may be helpful at https://gitter.im/haskell-gi/haskell-gi.
It should be rather easy to generate bindings to any library with gobject-introspection
support, see the examples in the bindings folder. Pull requests appreciated!
The bindings in haskell-gi
aim for complete coverage of the bound APIs, but as a result they are imperative in flavour. For nicer, higher-level approaches based on these bindings, see: