Convenient creation of command-line-driven executables for rendering diagrams using the Canvas backend.

• defaultMain creates an executable which can render a single diagram at various options.
• multiMain is like defaultMain but allows for a list of diagrams from which the user can choose one to render.
• mainWith is a generic form that does all of the above but with a slightly scarier type. See Diagrams.Backend.CmdLine. This form can also take a function type that has a suitable final result (any of arguments to the above types) and Parseable arguments.

If you want to generate diagrams programmatically---i.e. if you want to do anything more complex than what the below functions provide---you have several options.

• Use a function with mainWith. This may require making Parseable instances for custom argument types.
• Make a new Mainable instance. This may require a newtype wrapper on your diagram type to avoid the existing instances. This gives you more control over argument parsing, intervening steps, and diagram creation.
• Build option records and pass them along with a diagram to mainRender from Diagrams.Backend.CmdLine.

For a tutorial on command-line diagram creation see http://projects.haskell.org/diagrams/doc/cmdline.html.