I just stumbled across the archives directory of my .emacs.d/archives/ . Here's the beginning of .../archives/gnu/archive-contents

 (ace-window .
         [(0 9 0)
        (0 2 0)))
          "Quickly switch windows." single
          ((:url . "https://github.com/abo-abo/ace-window")
           (:keywords "window" "location"))])
 (ack .
      [(1 5)
       nil "interface to ack-like tools" tar
       ((:keywords "tools" "processes" "convenience")
    (:url . "https://github.com/leoliu/ack-el"))]) ...

Can someone "deep in the lore" enlighten me to what this is about, specifically, how this s-expression AST(?) is built, on what criteria. What is the data schema used here, et cetera....

  • This question is really too broad ("What is this about?"), and you pose several questions in it. And then you pose more questions in comments to @wasamasa's answer. And then you add another, separate question that is nearly identical, and nearly as broad. Q&A for this site should be specific, typically how-to, questions. Asking what considerations were involved in designing a particular package repository (or even a particular library) is too broad to be useful here, IMHO. You might want to try a site such as Reddit, which is more geared toward discussion. – Drew Jun 21 at 22:55

This is a list of packages available in the specific ELPA repository. It's created by the admin of that repository and downloaded by Emacs to know what's installable.

Here's a pseudo-grammar:

PACKAGE-NAME: <symbol>
VERSION: (<integer> ...)
TYPE: single | tar
METADATUM: (<keyword> ARG ...)
  • Know where the code is that handles (creates, reads) these archive files? – 147pm Feb 28 '17 at 2:31
  • It's in package.el, package-x.el contains a bit more for uploading and publishing packages. – wasamasa Feb 28 '17 at 7:27
  • Can anyone show me more of these sorts of "in the wild" uses of s-expressions for data management? I'm really needing to get my head around this -- beyond the baby examples in Lisp/Scheme textbooks. If not anyone reading this, then maybe suggest the proper forum(s)? Also, as a beginner, I'm not really grokking your "pseudo-grammar" wasamasa. Can you direct me to a tutorial of this pseudo-grammar? – 147pm Feb 28 '17 at 18:17
  • Read actual lisp source code and you'll discover more of these. There is no tutorial for this grammar because I made it up on the spot and consider it pretty easy to read: "Package-archives are a list of a package-archive-version and one or more packages, packave-archive-version is an integer, package is a cons of a package-name and a package-descriptor, package-name is a symbol, etc.". – wasamasa Feb 28 '17 at 20:09

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