diagrams-cairo is a rendering backend for diagrams, a powerful, flexible, declarative domain-specific language for creating vector graphics, using the Haskell programming language.

diagrams-cairo is implemented using the cairo rendering engine and is a fully-featured, officially supported backend for diagrams.

cabal update && cabal install gtk2hs-buildtools diagrams-cairo

A simple example that uses diagrams-cairo to draw a blue circle:

import Diagrams.Prelude
import Diagrams.Backend.Cairo.CmdLine

d = circle 1 # fc blue

main = defaultMain (pad 1.1 d)

Save this to file named Circle.hs and compile it:

ghc --make Circle.hs

This will generate an executable which, when run, outputs a blue circle to some file. Run the executable with the --help option to find out more about how to call it.

$ ./Circle --help
Command-line diagram generation.

Circle [OPTIONS]

Common flags:
  -w --width=INT    Desired width of the output image
  -h --height=INT   Desired height of the output image
  -o --output=FILE  Output file
  -? --help         Display help message
  -V --version      Print version information

The output type will be automatically determined from the file extension. Currently PNG, PDF, PS, and SVG are supported.

$ ./Circle -o circle.png -w 400

The command above generates a PNG file with a width of 400px.

Instead of just creating a standalone executable, the cairo backend can also be called from within a larger program. For more information, see the Diagram.Backend.Cairo module.