Plot one pixel in blue on a canvas

[Alain De Vos]

I want to plot a pixel in blue at coordinates (100,100) on a 
canvas of size (200,200)
I think i can use the arsd module.
But i have no idea what "dub add" comment I should use.
What i should import
How this demo program would look.
Cfr,
https://www.reddit.com/r/scala/comments/1h2g8a2/simple_graphics_api/
https://www.reddit.com/r/fsharp/comments/1h2g7pv/simple_graphics_api/