Metadata on pagenodes (?) / how to render link traversal

[femtomc]

I have two related questions (related in the sense that they motivated a common solution, but the solution is outside of pollen, and I was hoping I could somehow not resort to it).

I have an index.html.pm file -- I want to render an itemized list of the nodes in my pagetree (and I have an associated index.ptree file I curate). However, I want to render them with their titles (distinct from their node name). As far as I can tell, there's no way to attach metadata to page nodes -- except by keeping some state (a finite map, say) around (and then, when the preprocessor ingests a file, tell it to add a key with the current page node name, with value the metadata I want). The one thing I'm concerned about is the order of the traversal -- if the state is not updated before index.html.pm is preprocessed, that's going to be a problem.

The second question is about rendering the forward / backward links in a graphical form. I know that pollen must do this already (right?) -- I want to render a "knowledge graph" like representation of the link traversal. Is it possible to gain access to this structure through normal Racket? The alternative solution I had was another "stateful" thing where I keep a database around, and register forward/backward links in the database. I don't really want to do this, so I was hoping that there is an easier solution.

[femtomc]

Re -- I realized the first one was easy enough to work on:

◊(apply ol (map (lambda (node) `(li (a ((href ,(symbol->string node)))
        ,(car (select-from-doc 'h1 node)))))
        (pagetree->list (get-pagetree "index.ptree")))
)

e.g. this just uses the curated .ptree and a search over X-expressions to get the right thing.

The second one (forward and back links) I'm still stumped on.

[mbutterick]

As far as I can tell, there's no way to attach metadata to page nodes

Why not define-meta?

The second question is about rendering the forward / backward links in a graphical form. I know that pollen must do this already (right?)

The forward & backward links can be computed from a pagetree. (They could be computed other ways too.) But no, Pollen does not automatically render them “in a graphical form” — you would do that yourself.

I want to render a "knowledge graph" like representation of the link traversal

What does this mean — a graph of all the hyperlinks between pages? If so, I don’t see any alternative to reading the link tags out of the source files (assuming the links of interest are already tagged there; if not you would have to read & parse the output files) and imperatively building a graph. Racket’s graph library will output to graphviz format, so once you have a graph object, it’s easy to get a rendered diagram. (Not necessarily a pretty diagram, though.)

[mbutterick]

The second one (forward and back links) I'm still stumped on.

This is covered in the second tutorial in the Pollen docs.

[femtomc]

@mbutterick -- I'm looking into pollen/core more, I realized I misunderstood that you could access metadata about the document directly (e.g. by using the pagenode reference).

Right, so basically: iterate over nodes in the page tree, and grab all "special" links (e.g. cross links to other nodes), then offload to graphviz.

I'm pretty close now, thanks for the help!

[femtomc]

The forward & backward links can be computed from a pagetree. (They could be computed other ways too.) But no, Pollen does not automatically render them “in a graphical form” — you would do that yourself.

Here, I did a poor job -- I meant the traversal across the nodes (not the rendering).