[Chart] New stateful API

[Tim Docker]

Hi,

I’ve never liked the Simple API very much, and last week I played with a stateful API for constructing charts. I think it turned out reasonably well: it’s as flexible as constructing the layout records explicitly,  but is more concise. Producing a basic chart is a one liner.

Some examples of it’s use are here:

https://github.com/timbod7/haskell-chart/wiki/Monadic-API

The code to implement it is here:

https://github.com/timbod7/haskell-chart/blob/master/chart/Graphics/Rendering/Chart/State.hs

Any comments or feedback? I’d like to replace Simple with this. I don’t think the Simple API has m(any?) users in any case.

Tim