UI element for plotting graphs

[AshleyYakeley]

Options:

• Chart (updated recently), backends for cairo and diagrams
  • no backend for haskell-gi
• Other libraries: plot, QuickPlot: small, not recently updated
• Create new library based on The Grammar of Graphics
  • R library ggplot2
  • Old GSOC proposal

Discussion from 2016.

[AshleyYakeley]

• Chart backend for diagrams: Chart-diagrams
• diagrams backend for cairo: diagrams-cairo
• cairo backend for haskell-gi: gi-cairo, gi-cairo-render

Some question over different cairo libraries?

[AshleyYakeley]

Making good progress with the "Chart → diagrams → Cairo → GTK" pipeline.

Related: diagrams/diagrams-cairo#76 for that second arrow.

[AshleyYakeley]

Probably best to follow the Haskell types where possible.

Renderable makes sense to be a supertype of various things:

Layout <: Renderable StackedLayout <: Renderable Rectangle <: Renderable etc.

[AshleyYakeley]

Layout is a bit awkward, as there is Layout and LayoutLR, which share a number of fields.

Throughout this module, from a "lens" perspective we are interested in setting or constructing fields, but not getting them. In any case, we certainly want a "default with modifications" approach, rather than having to construct every field of a structure.

[AshleyYakeley]

Could do something like this:

• Layout <: Renderable
• [Layout] <: Layout
• layoutXAxis: Axis -> Layout
• layoutYAxis: Axis -> Layout
• layoutPlot: Plot -> Layout

etc.

[AshleyYakeley]

What about different plot scales? Double, Time, Integer, etc.

[AshleyYakeley]

• [Renderable] <: Renderable
• Layout <: Renderable
• layoutTitle: Text -> Layout -> Layout -- etc. for setting properties
• layout: Axis x -> Axis y -> [Plot x y] -> Layout
• layoutLR: Axis x -> Axis y1 -> Axis y2 -> [Either (Plot x y1) (Plot x y2)] -> Layout (Axis witnesses Ord constraint.)

[AshleyYakeley]

Maybe fix "Chart → Cairo", to simplify pipeline.

[AshleyYakeley]

Alternative: create our own approach based on ggplot2, using Cairo.