I have been learning Racket to make a footprint editor for KiCAD. KiCAD is a software for creating electronics PCBs and a footprint is a drawing of the PCB layers for a landing pattern for a particular electronic component. https://github.com/kasbah/footwork

The idea is pretty much a sketch-n-sketch approach to footprint editing. https://ravichugh.github.io/sketch-n-sketch/index.html

Choosing Racket for this application was a no brainer as it demands data-code intermingling with an s-expression based format and redefining the language to suite the application. Racket also has excellent GUI library that allowed me to get a graphics pane and a text-editor GUI up very quickly.

The APIs that Racket libraries provide seem a bit like quantity over quality to me. I dread having to sift though the docs for the functions I actually need. On the one hand every function is thoroughly documented on the other the descriptions are often seeped in the jargon surrounding the language.

For instance, this may be a stupid beginner mistake, but I couldn't work out how to make `send` and `apply` work together. Coming from Haskell I assumed there would be straight forward way to compose these things. Instead I had to resort to use the `send/apply` function and there seem to be a lot of these special purpose functions all over the place that are trying to anticipate your usage rather than providing composable primitives.