@lvh I don't think specter will be very useful for that

@nathanmarz is there a recursive-path that will not recurse into the transformed value? i.e. (recursive-path [] p [(walker vector?) (stay-then-continue ALL p)]) will go for a while, but I'm still finding something will stackoverflow... core.async, futures, apache client. I'm thinking I need to just run transforms again and again, until it no longer transforms rather than in one big recursive blitz

in the stack overflow error, there's lots of repeating versions of this:

@albaker that path is defined so it will continue recursing

recursive-path itself doesn't do anything besides provide you the programmer the ability to have the path refer to itself

if it's stack overflowing, then you're doing something wrong in your program

I'm okay recursing, just not into the results, so I recurse down to the last known genration, apply and end

I don't know what that means

whatever logic you want will need to be encoded in the path

you can use value collection to keep track of how many levels you've recursed

and then check that using collected? to have the path decide whether or not to recurse

or you can encode in your data itself information to allow the path to decide whether to recurse

e.g. using metadata

yeah, something like that - right now I'm keeping a counter ref going

yea, that would work too

lots of options available to control termination

there is a potential for a loop, and I thought I had caught it - but perhaps not

there a way to force the transform with recursive path to bail out?

you mean with an exception or something?

yeah, I guess just a regular exception and wrap the transform in a try/catch

I guess you could make a navigator which does that

try catch over invoking next-fn, and when your special exception is thrown it returns the structure unchanged

ok, I'll take a look at that - thanks!

imo that's a dirty way to solve this and you're better off more precisely specifying when you want recursion to stop

it's using exceptions for flow control

yeah

ah sweet, found the bug, took the exception out, and now have a near general purpose specter+stardog graph walker for recursively expanding graph data

@nathanmarz thanks for all the help - this is really nice, with like 6 lines of specter, and a few lines of SPARQL, this thing walks and queries and walks again. I'll give a shot out in the blog that'll fall out from this

@albaker no problem, happy to help

I have a (maybe similar?) question. Happy to post on StackOverflow if I can formulate it correctly. I think the imaginary code I want may explain best:

(def TreeValues
  (s/recursive-path [] p
    (s/if-path #(not (empty? (:children %)))
      (s/submap [:id :name {{ set :children to [:children s/ALL p] }}  ])
      (s/submap [:id :name :children]))))

is this possible without an inner transform? Maybe with some use of collect that I haven’t hit on yet?

essentially it’s operating on a vector of maps, where each map has a :children key with a vec of the same type of map

I’m just trying to prune each level to the keys I want

submap isn't going to prune keys

it lets you operate on a portion of the map with the result being merged back into the original map

I think you want to use continue-then-stay

hmm, OK thanks. I got the notion of pruning because this is the closet I got, but it only returns the leaves

(recursive-path [] p (continue-then-stay :children ALL p))

(def TreeValues
  (s/recursive-path [] p
    (s/if-path #(not (empty? (:children %)))
      [:children s/ALL p]
      (s/submap [:id :name :children]))))

then you could do: (transform TreeNodes #(select-keys % [:id :name :children]) data)

ok, thanks - reading up on continue-then-stay and trying it out

that works, thanks!

I’m lacking some intuition though . . . I don’t understand why this works:

(transform [ALL TreeNodes] #(select-keys % [:id :name :children]) data)

(transform [FIRST TreeNodes] #(select-keys % [:id :name :children]) data)

what's not working?

the latter does something, I’m not sure what, on the whole data vec. I thought it would be equivalent to:

(transform [ALL TreeNodes] #(select-keys % [:id :name :children]) (take 1 data))

no, it will just do the transformation on the first element of the vector

you'll still get the whole vector back, but everything beyond the first element will be untouched

oh, got it

transform always operates on a select portion of the data structure, with the path specifying how to navigate to what needs to be operated on

makes sense, I think I understood that but just dropped the context of the basics when struggling with this problem. Thanks