How to read the generateCode chart

[cd155]

I am not quite sure I understand this chart correctly, so I wonder if someone could explain how to read this chart.

In the brook thesis, this chart shows how the result of genPackage is processed by generateCode to generate files in the user’s system. And arrows represent function calls, and boxes show the type each call results in.

This is the generateCode method. https://github.com/JacquesCarette/Drasil/blob/4d0ba25ce5037a2474cf7b6b28eb5154f7c11a7e/code/drasil-code/lib/Language/Drasil/Code/Imperative/Generator.hs#L101-L113

From the beginning, what is Reader DrasilState, and then what is the runReader? It would be great to be guided a little bit on how to read this chart.

[JacquesCarette]

It's a dataflow diagram, with the arrows representing the functions applied and the boxes the types.

The code doesn't quite match, since it's using runState instead of runReader. Also, it calls unReprPack twice (on the same argument) to get at both pieces. The state/reader disconnect happened because this code used to use just reader, but state was added later. It's kind of a good example of why we need Drasil: the documentation became out-of-date with the code!

[cd155]

Thanks @JacquesCarette , I also add some notes for last week's meeting.

The following is the note for the Jan 21st, 2022 discussion

The workflow for this chart

• Reader: this is a data structure that will be processed in reader monad
• Reader Constructor takes Drasil state, and (packRepr (Package packRepr)
• The Reader is packed, so we need to instantiate it (unReprPack), then it will give you a PackData
• The PackData split into the program(ProgData) and various auxiliary files
• A program made up by modules (the list of files on the left under ProgData)
• Left files([FileData]) and right files([AuxData]) will assemble again, to generate all the code, including code, headers files, make files
• Doc is the pretty printed version of each artifact
• FilePath is the pass to where the file will be

Notes

• runState (genPackage unReprProg) g takes a package representation, and give you the data structure, PackData
• packRepr is a type variable,
• function (packRepr (Package packRepr) -> PackData) removes the polymorphism of packRepr, and create useful data (PackData)
• "un-" prefix used in this case. When there is a constructor for a data type, and it has no name and it is also a new type that has only one filed, we add "un-" to the field accessor.