- nix-org-babel
This is an implementation of =org-babel-tangle= in Nix.
Given an Org string, it extracts the contents of source blocks in a particular language.
Rationale
[[https://github.com/talyz/fromElisp][talyz/fromElisp]] provides support for Org, and it is also part of [[https://github.com/nix-community/emacs-overlay][emacs-overlay]], which apparently is used by many people for their own configs.
However, I wanted to experiment with more advanced features such as excluding archived entries, and I wasn't sure if I could mix that with their code base.
I needed the feature in [[https://github.com/akirak/emacs-twist][my own project]], and I wanted to put it under my control, so I wrote it from scratch.
Usage
Import the flake.
* Extracting source blocks from an Org file/string
** tangleOrgBabel function
This function takes an Org string and returns its source blocks.
Example:
+begin_src nix
let
tangle = lib.tangleOrgBabel {
languages = [ "emacs-lisp" ];
};
in
Return a string
tangle (builtins.readFile ./config.org)
+end_src
Arguments:
- An attribute set of options.
- An Org input string.
**** tangleOrgBabelFile function
Similar to =tangleOrgBabel=, but this function takes a file as an argument and writes the output to a file.
Example:
+begin_src nix
Write to a file
let
pkgs = import nixpkgs {
inherit system;
overlays = [
org-babel.overlays.default
];
};
in
pkgs.tangleOrgBabelFile "init.el" ./config.org {
languages = [ "emacs-lisp" ];
}
+end_src
Note that this function is provided in the overlay of the flake.
Arguments:
- A string for the derivation name.
- An input file path.
- An attribute set of options.
* Options
** Languages
Example:
+begin_src nix
{
languages = [ "emacs-lisp" "elisp" ];
}
+end_src
Default: =[ "emacs-lisp" "elisp" ]=
**** Filtering subtrees
You can transform the input by specifying =processLines= option.
It must be a function that takes a list of strings and returns a list of strings.
This library also contains =excludeHeadlines= function which can be used to exclude subtrees according to a predicate on the headline text, so you can use it in the option.
Example:
+begin_src nix
{
Exclude archived subtrees
processLines = excludeHeadlines (matchOrgTag "ARCHIVE");
}
+end_src
You can use the following predicates from this library:
- tag :: Returns true if the headline matches a tag given as the argument. The argument must be a string.
- headlineText :: Returns true if the headline matches the text given as the argument. The argument must be a string.