Add rhine-cassava

[turion]

• Clean up git history
• Add a few more CSV tests
• Add a few file unit tests
• Use in a bigger example
• Add CSV writing tools
• Timestamping from CSVs, where one can maybe specify the timestamp column

[turion]

Consider adding a Frames clock as well (or instead): https://hackage.haskell.org/package/Frames

[turion]

Document how the CSV file needs to be formatted, probably in the module doc

[turion]

Naming: Better call it Csv?

[turion]

This is a bit inconsistent in the code base. I think I've sometimes called something e.g. SelectClock to avoid clashing with Select (an obscure monad transformer). But in principle it would be nicer not to have Clock in the name every time.

[turion]

Csv clashes prominently with a type of the same name from cassava. I could call it CsvRow or something like that. But CsvClock is more memorable.

[turion]

CsvRecord? And a corresponding better name for the parsing variant?

[turion]

Maybe a better hierarchy would be:

FRP.Rhine.Csv.Clock -- this module
FRP.Rhine.Csv -- Csv utils like CSV writer ClSF, and clock reexport

[turion]

It would be nice if the clock automatically did the parsing (and throws an error if it fails)

[turion]

I've observed runtime errors with this approach in the wild. Possibly, the way I'm reading the file here isn't that good, and instead I should use the streaming interface https://hackage.haskell.org/package/cassava-0.5.3.0/docs/Data-Csv-Streaming.html#g:2 But this would mean not reusing the file clock. Which is fine.

[turion]

I've observed runtime errors with this approach in the wild.

I definitely need hardened tests that would have detected these errors.