From d3c44b7fec5c63b63eaa61a159043c06d19d46b5 Mon Sep 17 00:00:00 2001
From: Akira Komamura <akira.komamura@gmail.com>
Date: Sun, 12 Dec 2021 05:18:46 +0900
Subject: [PATCH] fix!: Provide the file writer in an overlay

builtins.toFile doesn't work in pure evaluation mode. It must use
a function from nixpkgs, so it should be provided in an overlay.
---
 flake.nix       | 13 ++++++++++++-
 nix/default.nix |  4 ----
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/flake.nix b/flake.nix
index ce938c4..f0a27c1 100644
--- a/flake.nix
+++ b/flake.nix
@@ -1,5 +1,16 @@
 {
   description = "Nix library for extracting source blocks from Org";
 
-  outputs = { ... }: { lib = import ./nix; };
+  outputs = { ... }:
+    let
+      lib = import ./nix;
+    in
+      {
+        inherit lib;
+        overlay = _: pkgs: {
+          tangleOrgBabelFile = name: path: options:
+            pkgs.writeText name
+              (lib.tangleOrgBabel options (builtins.readFile path));
+        };
+      };
 }
diff --git a/nix/default.nix b/nix/default.nix
index 1c61189..f9f2cb3 100644
--- a/nix/default.nix
+++ b/nix/default.nix
@@ -8,13 +8,9 @@ let
     builtins.any (t: matchOrgHeadline t s) headlines;
 
   tangleOrgBabel = import ./tangleOrgBabel.nix;
-
-  tangleOrgBabelFile = name: path: options:
-    toFile name (tangleOrgBabel options (readFile path));
 in
 {
   inherit matchOrgTag matchOrgHeadline matchOrgHeadlines;
   inherit excludeOrgSubtreesOnHeadlines;
   inherit tangleOrgBabel;
-  inherit tangleOrgBabelFile;
 }