mirror of
https://github.com/privatevoid-net/nix-super.git
synced 2024-12-02 18:36:15 +02:00
31313d1401
They are equivalent according to <https://spec.commonmark.org/0.29/#hard-line-breaks>, and the trailing spaces tend to be a pain (because the make git complain, editors tend to want to remove them − the `.editorconfig` actually specifies that − etc..).
20 lines
737 B
Markdown
20 lines
737 B
Markdown
# Built-in Constants
|
||
|
||
Here are the constants built into the Nix expression evaluator:
|
||
|
||
- `builtins`\
|
||
The set `builtins` contains all the built-in functions and values.
|
||
You can use `builtins` to test for the availability of features in
|
||
the Nix installation, e.g.,
|
||
|
||
```nix
|
||
if builtins ? getEnv then builtins.getEnv "PATH" else ""
|
||
```
|
||
|
||
This allows a Nix expression to fall back gracefully on older Nix
|
||
installations that don’t have the desired built-in function.
|
||
|
||
- `builtins.currentSystem`\
|
||
The built-in value `currentSystem` evaluates to the Nix platform
|
||
identifier for the Nix installation on which the expression is being
|
||
evaluated, such as `"i686-linux"` or `"x86_64-darwin"`.
|