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author | Eelco Dolstra <e.dolstra@tudelft.nl> | 2004-10-25T16·54+0000 |
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committer | Eelco Dolstra <e.dolstra@tudelft.nl> | 2004-10-25T16·54+0000 |
commit | 37d7abd69402f0e7a78d4d2f2d78996409a8563a (patch) | |
tree | bf844e4486b0e055921583c4b7c2d3d843b34485 /doc | |
parent | f4d44a002688262d33093494a7fea1bb11b97ac9 (diff) |
* New language feature: with expressions.
The expression `with E1; E2' evaluates to E2 with all bindings in the attribute set E1 substituted. E.g., with {x = 123;}; x evaluates to 123. That is, the attribute set E1 is in scope in E2. This is particularly useful when importing files containing lots definitions. E.g., instead of let { inherit (import ./foo.nix) a b c d e f; body = ... a ... f ...; } we can now say with import ./foo.nix; ... a ... f ... I.e., we don't have to say what variables should be brought into scope.
Diffstat (limited to 'doc')
-rw-r--r-- | doc/manual/package-management.xml | 34 |
1 files changed, 21 insertions, 13 deletions
diff --git a/doc/manual/package-management.xml b/doc/manual/package-management.xml index 470cb80a09e1..b717844b1141 100644 --- a/doc/manual/package-management.xml +++ b/doc/manual/package-management.xml @@ -17,18 +17,12 @@ available for installation.</para> <para>In Nix, different users can have different <quote>views</quote> on the set of installed applications. That is, there might be lots of applications present on the system (possibly in many different -versions), but users can have a specific selection of those -active — where <quote>active</quote> just means that it appears -in a directory in the user's <envar>PATH</envar>.</para> - -<para>Such a view on the set of installed applications is called a -<emphasis>user environment</emphasis>, which is just a directory tree -consisting of symlinks to the files of the active applications. In -Nix, operations such as upgrading or removing components never -overwrite or remove the files of those components, and they don't even -touch the user environments that point to them. Rather, they cause a -<emphasis>new</emphasis> user environment to be constructed based on -the old one.</para> +versions), but users can have a specific selection of those active — +where <quote>active</quote> just means that it appears in a directory +in the user's <envar>PATH</envar>. Such a view on the set of +installed applications is called a <emphasis>user +environment</emphasis>, which is just a directory tree consisting of +symlinks to the files of the active applications. </para> <para>Components are installed from a set of <emphasis>Nix expressions</emphasis> that tell Nix how to build those components, @@ -168,7 +162,21 @@ set.</para></footnote></para> <sect1><title>Profiles</title> -<para>Bla</para> +<para>In Nix, operations such as upgrading or removing components +never overwrite or remove the files of those components, and they +don't even touch the user environments that point to them. Rather, +they cause a <emphasis>new</emphasis> user environment to be +constructed based on the old one. This is illustrated in Figure +bla.</para> + +<figure><title>User environments</title> + <mediaobject> + <imageobject> + <imagedata fileref='figures/userenv-frame3.png' format='PNG' /> + </imageobject> + </mediaobject> +</figure> + </sect1> |