nix/flake.md: flakes do not evaluate metadata outside of outputs

cc NixOS#4945
ckiee · Jun 8, 2022 · 6f3c897 · 6f3c897
1 parent 388c457
commit 6f3c897
Showing 1 changed file with 8 additions and 0 deletions.
diff --git a/src/nix/flake.md b/src/nix/flake.md
@@ -282,6 +282,14 @@ derivation):
 }
 ```
 
+
+
+`flake.nix` is written in a limited subset of the Nix language
+in order to prevent metadata lookups from hanging; values must
+be written directly and indirect evaluations such as `let..in`
+are not permitted. This does not apply to the body of
+the `outputs` function.
+
 The following attributes are supported in `flake.nix`:
 
 * `description`: A short, one-line description of the flake.