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expand on interpolated expressions

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Valentin Gagarin 2023-10-07 02:27:06 +02:00
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12
doc/manual/src/language/values.md
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@ -112,18 +112,16 @@
environment variable `NIX_PATH` will be searched for the given file
or directory name.
When an [interpolated string][string interpolation] evaluates to a path, the path is first copied into the Nix store and the resulting string is the [store path] of the newly created [store object].
[store path]: ../glossary.md#gloss-store-path
[store object]: ../glossary.md#gloss-store-object
For instance, evaluating `"${./foo.txt}"` will cause `foo.txt` in the current directory to be copied into the Nix store and result in the string `"/nix/store/<hash>-foo.txt"`.
Note that the Nix language assumes that all input files will remain _unchanged_ while evaluating a Nix expression.
For example, assume you used a file path in an interpolated string during a `nix repl` session.
Later in the same session, after having changed the file contents, evaluating the interpolated string with the file path again might not return a new store path, since Nix might not re-read the file contents.
Later in the same session, after having changed the file contents, evaluating the interpolated string with the file path again might not return a new [store path], since Nix might not re-read the file contents.
Paths themselves, except those in angle brackets (`< >`), support [string interpolation].
[store path]: ../glossary.md#gloss-store-path
Paths, except those in angle brackets (`< >`), support [string interpolation] and can be used in [interpolated expressions].
[interpolated expressions]: ./string-interpolation.md#interpolated-expressions
At least one slash (`/`) must appear *before* any interpolated expression for the result to be recognized as a path.