allow supplying a custom metadata format parser for compiler

[lennart]

currently hakyll seems to be only able to read metadata as YAML (as far as I understand the code in Provider/Metadata.hs)

I want to be able to have hakyll keep source code function documentation in metadata as key value pairs (functionname: functiondocstring) when compiling source code files.

big picture is

• route to a pattern of haskell source files, compile with a custom Compiler
• then build a map of all functions (docs) found in all files given by a pattern (similar to buildTags but not quite)
• then write function references within markdown pages as standard yaml metadata list field
• build a map of those function references
• match them against the function docs by their identifiers (function names)
• render the markdown page with content & a list of rendered functionname/functiondocstrings

So in order to do that (as the docstrings do not appear in single files and I cannot find another way to do the above) I was thinking of a custom Metadata parser (I can provide) that essentially parses haskell source code into an AST and extracts the function names and docstrings into a Metadata object.

How would that be possible? I am not hesitant to put this into a contrib module, as I fear this is a rather non-standard feature request.

However right now, I think I would need to fork hakyll in order to do that, and I would rather not.

suggestions on how to proceed?

kindly,

lennart

[jaspervdj]

I don't think you necessarily need to do this through metadata, I think you can approach it from a different angle as well.

What I suggest is the following flow:

1. Compile all source files to a custom datatype (e.g. DocMap). Use a version "docmap" here to distinguish it.
2. Add a compiler which loads all DocMaps produced in (1) and mconcats them together to get a "global" DocMap.
3. Compile all source files "normally" but load the global DocMap so you can use that to render the table of context and so on.