diagrams

Current status

This is my playground for rewriting diagrams. It's currently at the proof of concept stage. I've implemented most of the core functionality of diagrams with significant changes in some places. I've also added some new features.

The only backend I've ported so far is diagrams-pgf on the diagrams-2.0 branch.

I've also started a very basic 3d gl and sdl backend that does spheres, cubes and straight lines shapes. You can move the camera around but that's about it.

Changes

Reshuffling

diagrams-core and diagrams-lib would no longer be used. diagrams and geometry would be used instead. geometry is a new library based on diagrams-lib. One advantage is that geometry could be used by other libraries that don't want to depend on diagrams (whereas diagrams-core can only be used by diagrams-lib). Many of the old core modules have moved to Diagrams.Types.X. The functionality of dual-tree has been moved to Diagrams.Types.Tree.

New features

Some of the major proposed changes include:

• The backend token is gone. The Diagram alias now only takes the vector space used (so Diagram V2 or Diagram V3). This will ease a lot of pain I've had with plots and allows lots of new features that hard or close to impossible with the current tokened diagram.

• Named subdiagram traversals! You can traversal over diagrams that matching or include a name. The way diagrams are named has also changed significantly. It's also possible to traverse over styles and primitives (like paths etc.).

There are also some smaller changes:

• mainWith now takes a backend token to decide which backend to use. There is also functionally to use mainWith with multiple backends in the same executable.

• Rewrite of Style internals for better type safety. The interface is now entirely lens based. Backends no longer deal with styles and instead receive an Attributes which is just a map from TypeRep to Dynamic (no transformable or measured attributes).

• Static annotations (group opacity, hrefs etc.) are now extensible, just like styles. They are also transformable so Clip has been moved to a static annotation.

• Down annotations are stricter. The Transformation type is in matrix form, giving us proper O(1) transforms.

• Up annotations are no longer cached at the top. Among other things this means we could traverse parts of a diagram depending of the result of querying an up annotation (not yet implemented).

• The Alignable class has been removed. Alignment functions now use enveloped. (The previous Alignable instances either used enveloped anyway, or had bogus definitions (like for functions)). This also lets us make more performant definitions for things like hcat.

Other possible changes:

• Limit diagrams back to double again? The geometry library would still allow any number type for better precision etc. but I can't think of any reason to use anything but double for a diagram. I've already limited a bunch of things to double (ToTexture, Backend) and it makes things much easier.