WIP Macro syntax

[davidanthoff]

I played around with a @vlplot macro today. I kind of like it, I have to say :) I translated a whole bunch of specs from the vega-lite examples, you can see them here and here. The pattern is that I first plot the JSON version, and then translate the figure into the @vlplot syntax below.

I guess the key aspect of this is that everything mimics the JSON really closely. Essentially one just has to remove a couple of ", and replace : with =, and otherwise it is pretty much the same syntax. So I think that would have enormous benefits in terms of documentation etc....

I also added a bunch of shortcuts. In particular:

• One can write enc instead of encoding.
• One can use the altair shortcut notation a la sum(field):q.
• For marks and field definitions, one can write something like x={"field:q",axis=nothing}. The major benefit over a standard named tuple is that here we can have a positional thing ("field:q") and a keyword thing.

The layered etc. part is not great yet. Here is what I have so far:

• p1 + p2 will add a layer element to p1 and put p2 into that. I think that works fairly well.
• I did do the hcat and vcat thing again, but not so sure about that...
• I haven't really looked at faceting etc., that probably requires more thinking.

I think this strategy has two things going for it: 1) for simple plots, everything ends up pretty concise (data |> @vlplot(:point,enc={x=:foo,y=:bar}) I think is pretty good), 2) it is close to the JSON.

What do you think? I'll also keep playing with your idea from #69 just to compare.

[davidanthoff]

And I've started porting stuff from the altair examples here and here.

So far I've not run into any difficulty, and in most cases I think our syntax is quite nice for these examples...