diff options
author | Alyssa Ross <hi@alyssa.is> | 2019-01-07 02:18:36 +0000 |
---|---|---|
committer | Alyssa Ross <hi@alyssa.is> | 2019-01-07 02:18:47 +0000 |
commit | 36f56d99fa0a0765c9f1de4a5f17a9b05830c3f2 (patch) | |
tree | b3faaf573407b32aa645237a4d16b82778a39a92 /nixpkgs/doc/functions | |
parent | 4e31070265257dc67d120c27e0f75c2344fdfa9a (diff) | |
parent | abf060725d7614bd3b9f96764262dfbc2f9c2199 (diff) | |
download | nixlib-36f56d99fa0a0765c9f1de4a5f17a9b05830c3f2.tar nixlib-36f56d99fa0a0765c9f1de4a5f17a9b05830c3f2.tar.gz nixlib-36f56d99fa0a0765c9f1de4a5f17a9b05830c3f2.tar.bz2 nixlib-36f56d99fa0a0765c9f1de4a5f17a9b05830c3f2.tar.lz nixlib-36f56d99fa0a0765c9f1de4a5f17a9b05830c3f2.tar.xz nixlib-36f56d99fa0a0765c9f1de4a5f17a9b05830c3f2.tar.zst nixlib-36f56d99fa0a0765c9f1de4a5f17a9b05830c3f2.zip |
Add 'nixpkgs/' from commit 'abf060725d7614bd3b9f96764262dfbc2f9c2199'
git-subtree-dir: nixpkgs git-subtree-mainline: 4e31070265257dc67d120c27e0f75c2344fdfa9a git-subtree-split: abf060725d7614bd3b9f96764262dfbc2f9c2199
Diffstat (limited to 'nixpkgs/doc/functions')
-rw-r--r-- | nixpkgs/doc/functions/debug.xml | 21 | ||||
-rw-r--r-- | nixpkgs/doc/functions/dockertools.xml | 564 | ||||
-rw-r--r-- | nixpkgs/doc/functions/fhs-environments.xml | 142 | ||||
-rw-r--r-- | nixpkgs/doc/functions/generators.xml | 89 | ||||
-rw-r--r-- | nixpkgs/doc/functions/library.xml | 15 | ||||
-rw-r--r-- | nixpkgs/doc/functions/library/asserts.xml | 117 | ||||
-rw-r--r-- | nixpkgs/doc/functions/library/attrsets.xml | 1731 | ||||
-rw-r--r-- | nixpkgs/doc/functions/overrides.xml | 212 | ||||
-rw-r--r-- | nixpkgs/doc/functions/shell.xml | 26 |
9 files changed, 2917 insertions, 0 deletions
diff --git a/nixpkgs/doc/functions/debug.xml b/nixpkgs/doc/functions/debug.xml new file mode 100644 index 000000000000..c6b3611eea53 --- /dev/null +++ b/nixpkgs/doc/functions/debug.xml @@ -0,0 +1,21 @@ +<section xmlns="http://docbook.org/ns/docbook" + xmlns:xlink="http://www.w3.org/1999/xlink" + xmlns:xi="http://www.w3.org/2001/XInclude" + xml:id="sec-debug"> + <title>Debugging Nix Expressions</title> + + <para> + Nix is a unityped, dynamic language, this means every value can potentially + appear anywhere. Since it is also non-strict, evaluation order and what + ultimately is evaluated might surprise you. Therefore it is important to be + able to debug nix expressions. + </para> + + <para> + In the <literal>lib/debug.nix</literal> file you will find a number of + functions that help (pretty-)printing values while evaluation is runnnig. You + can even specify how deep these values should be printed recursively, and + transform them on the fly. Please consult the docstrings in + <literal>lib/debug.nix</literal> for usage information. + </para> +</section> diff --git a/nixpkgs/doc/functions/dockertools.xml b/nixpkgs/doc/functions/dockertools.xml new file mode 100644 index 000000000000..501f46a967c3 --- /dev/null +++ b/nixpkgs/doc/functions/dockertools.xml @@ -0,0 +1,564 @@ +<section xmlns="http://docbook.org/ns/docbook" + xmlns:xlink="http://www.w3.org/1999/xlink" + xmlns:xi="http://www.w3.org/2001/XInclude" + xml:id="sec-pkgs-dockerTools"> + <title>pkgs.dockerTools</title> + + <para> + <varname>pkgs.dockerTools</varname> is a set of functions for creating and + manipulating Docker images according to the + <link xlink:href="https://github.com/moby/moby/blob/master/image/spec/v1.2.md#docker-image-specification-v120"> + Docker Image Specification v1.2.0 </link>. Docker itself is not used to + perform any of the operations done by these functions. + </para> + + <warning> + <para> + The <varname>dockerTools</varname> API is unstable and may be subject to + backwards-incompatible changes in the future. + </para> + </warning> + + <section xml:id="ssec-pkgs-dockerTools-buildImage"> + <title>buildImage</title> + + <para> + This function is analogous to the <command>docker build</command> command, + in that can used to build a Docker-compatible repository tarball containing + a single image with one or multiple layers. As such, the result is suitable + for being loaded in Docker with <command>docker load</command>. + </para> + + <para> + The parameters of <varname>buildImage</varname> with relative example values + are described below: + </para> + + <example xml:id='ex-dockerTools-buildImage'> + <title>Docker build</title> +<programlisting> +buildImage { + name = "redis"; <co xml:id='ex-dockerTools-buildImage-1' /> + tag = "latest"; <co xml:id='ex-dockerTools-buildImage-2' /> + + fromImage = someBaseImage; <co xml:id='ex-dockerTools-buildImage-3' /> + fromImageName = null; <co xml:id='ex-dockerTools-buildImage-4' /> + fromImageTag = "latest"; <co xml:id='ex-dockerTools-buildImage-5' /> + + contents = pkgs.redis; <co xml:id='ex-dockerTools-buildImage-6' /> + runAsRoot = '' <co xml:id='ex-dockerTools-buildImage-runAsRoot' /> + #!${stdenv.shell} + mkdir -p /data + ''; + + config = { <co xml:id='ex-dockerTools-buildImage-8' /> + Cmd = [ "/bin/redis-server" ]; + WorkingDir = "/data"; + Volumes = { + "/data" = {}; + }; + }; +} +</programlisting> + </example> + + <para> + The above example will build a Docker image <literal>redis/latest</literal> + from the given base image. Loading and running this image in Docker results + in <literal>redis-server</literal> being started automatically. + </para> + + <calloutlist> + <callout arearefs='ex-dockerTools-buildImage-1'> + <para> + <varname>name</varname> specifies the name of the resulting image. This is + the only required argument for <varname>buildImage</varname>. + </para> + </callout> + <callout arearefs='ex-dockerTools-buildImage-2'> + <para> + <varname>tag</varname> specifies the tag of the resulting image. By + default it's <literal>null</literal>, which indicates that the nix output + hash will be used as tag. + </para> + </callout> + <callout arearefs='ex-dockerTools-buildImage-3'> + <para> + <varname>fromImage</varname> is the repository tarball containing the base + image. It must be a valid Docker image, such as exported by + <command>docker save</command>. By default it's <literal>null</literal>, + which can be seen as equivalent to <literal>FROM scratch</literal> of a + <filename>Dockerfile</filename>. + </para> + </callout> + <callout arearefs='ex-dockerTools-buildImage-4'> + <para> + <varname>fromImageName</varname> can be used to further specify the base + image within the repository, in case it contains multiple images. By + default it's <literal>null</literal>, in which case + <varname>buildImage</varname> will peek the first image available in the + repository. + </para> + </callout> + <callout arearefs='ex-dockerTools-buildImage-5'> + <para> + <varname>fromImageTag</varname> can be used to further specify the tag of + the base image within the repository, in case an image contains multiple + tags. By default it's <literal>null</literal>, in which case + <varname>buildImage</varname> will peek the first tag available for the + base image. + </para> + </callout> + <callout arearefs='ex-dockerTools-buildImage-6'> + <para> + <varname>contents</varname> is a derivation that will be copied in the new + layer of the resulting image. This can be similarly seen as <command>ADD + contents/ /</command> in a <filename>Dockerfile</filename>. By default + it's <literal>null</literal>. + </para> + </callout> + <callout arearefs='ex-dockerTools-buildImage-runAsRoot'> + <para> + <varname>runAsRoot</varname> is a bash script that will run as root in an + environment that overlays the existing layers of the base image with the + new resulting layer, including the previously copied + <varname>contents</varname> derivation. This can be similarly seen as + <command>RUN ...</command> in a <filename>Dockerfile</filename>. + <note> + <para> + Using this parameter requires the <literal>kvm</literal> device to be + available. + </para> + </note> + </para> + </callout> + <callout arearefs='ex-dockerTools-buildImage-8'> + <para> + <varname>config</varname> is used to specify the configuration of the + containers that will be started off the built image in Docker. The + available options are listed in the + <link xlink:href="https://github.com/moby/moby/blob/master/image/spec/v1.2.md#image-json-field-descriptions"> + Docker Image Specification v1.2.0 </link>. + </para> + </callout> + </calloutlist> + + <para> + After the new layer has been created, its closure (to which + <varname>contents</varname>, <varname>config</varname> and + <varname>runAsRoot</varname> contribute) will be copied in the layer itself. + Only new dependencies that are not already in the existing layers will be + copied. + </para> + + <para> + At the end of the process, only one new single layer will be produced and + added to the resulting image. + </para> + + <para> + The resulting repository will only list the single image + <varname>image/tag</varname>. In the case of + <xref linkend='ex-dockerTools-buildImage'/> it would be + <varname>redis/latest</varname>. + </para> + + <para> + It is possible to inspect the arguments with which an image was built using + its <varname>buildArgs</varname> attribute. + </para> + + <note> + <para> + If you see errors similar to <literal>getProtocolByName: does not exist (no + such protocol name: tcp)</literal> you may need to add + <literal>pkgs.iana-etc</literal> to <varname>contents</varname>. + </para> + </note> + + <note> + <para> + If you see errors similar to <literal>Error_Protocol ("certificate has + unknown CA",True,UnknownCa)</literal> you may need to add + <literal>pkgs.cacert</literal> to <varname>contents</varname>. + </para> + </note> + + <example xml:id="example-pkgs-dockerTools-buildImage-creation-date"> + <title>Impurely Defining a Docker Layer's Creation Date</title> + <para> + By default <function>buildImage</function> will use a static date of one + second past the UNIX Epoch. This allows <function>buildImage</function> to + produce binary reproducible images. When listing images with + <command>docker list images</command>, the newly created images will be + listed like this: + </para> +<screen><![CDATA[ +$ docker image list +REPOSITORY TAG IMAGE ID CREATED SIZE +hello latest 08c791c7846e 48 years ago 25.2MB +]]></screen> + <para> + You can break binary reproducibility but have a sorted, meaningful + <literal>CREATED</literal> column by setting <literal>created</literal> to + <literal>now</literal>. + </para> +<programlisting><![CDATA[ +pkgs.dockerTools.buildImage { + name = "hello"; + tag = "latest"; + created = "now"; + contents = pkgs.hello; + + config.Cmd = [ "/bin/hello" ]; +} +]]></programlisting> + <para> + and now the Docker CLI will display a reasonable date and sort the images + as expected: +<screen><![CDATA[ +$ docker image list +REPOSITORY TAG IMAGE ID CREATED SIZE +hello latest de2bf4786de6 About a minute ago 25.2MB +]]></screen> + however, the produced images will not be binary reproducible. + </para> + </example> + </section> + + <section xml:id="ssec-pkgs-dockerTools-buildLayeredImage"> + <title>buildLayeredImage</title> + + <para> + Create a Docker image with many of the store paths being on their own layer + to improve sharing between images. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>name</varname> + </term> + <listitem> + <para> + The name of the resulting image. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>tag</varname> <emphasis>optional</emphasis> + </term> + <listitem> + <para> + Tag of the generated image. + </para> + <para> + <emphasis>Default:</emphasis> the output path's hash + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>contents</varname> <emphasis>optional</emphasis> + </term> + <listitem> + <para> + Top level paths in the container. Either a single derivation, or a list + of derivations. + </para> + <para> + <emphasis>Default:</emphasis> <literal>[]</literal> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>config</varname> <emphasis>optional</emphasis> + </term> + <listitem> + <para> + Run-time configuration of the container. A full list of the options are + available at in the + <link xlink:href="https://github.com/moby/moby/blob/master/image/spec/v1.2.md#image-json-field-descriptions"> + Docker Image Specification v1.2.0 </link>. + </para> + <para> + <emphasis>Default:</emphasis> <literal>{}</literal> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>created</varname> <emphasis>optional</emphasis> + </term> + <listitem> + <para> + Date and time the layers were created. Follows the same + <literal>now</literal> exception supported by + <literal>buildImage</literal>. + </para> + <para> + <emphasis>Default:</emphasis> <literal>1970-01-01T00:00:01Z</literal> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>maxLayers</varname> <emphasis>optional</emphasis> + </term> + <listitem> + <para> + Maximum number of layers to create. + </para> + <para> + <emphasis>Default:</emphasis> <literal>24</literal> + </para> + </listitem> + </varlistentry> + </variablelist> + + <section xml:id="dockerTools-buildLayeredImage-arg-contents"> + <title>Behavior of <varname>contents</varname> in the final image</title> + + <para> + Each path directly listed in <varname>contents</varname> will have a + symlink in the root of the image. + </para> + + <para> + For example: +<programlisting><![CDATA[ +pkgs.dockerTools.buildLayeredImage { + name = "hello"; + contents = [ pkgs.hello ]; +} +]]></programlisting> + will create symlinks for all the paths in the <literal>hello</literal> + package: +<screen><![CDATA[ +/bin/hello -> /nix/store/h1zb1padqbbb7jicsvkmrym3r6snphxg-hello-2.10/bin/hello +/share/info/hello.info -> /nix/store/h1zb1padqbbb7jicsvkmrym3r6snphxg-hello-2.10/share/info/hello.info +/share/locale/bg/LC_MESSAGES/hello.mo -> /nix/store/h1zb1padqbbb7jicsvkmrym3r6snphxg-hello-2.10/share/locale/bg/LC_MESSAGES/hello.mo +]]></screen> + </para> + </section> + + <section xml:id="dockerTools-buildLayeredImage-arg-config"> + <title>Automatic inclusion of <varname>config</varname> references</title> + + <para> + The closure of <varname>config</varname> is automatically included in the + closure of the final image. + </para> + + <para> + This allows you to make very simple Docker images with very little code. + This container will start up and run <command>hello</command>: +<programlisting><![CDATA[ +pkgs.dockerTools.buildLayeredImage { + name = "hello"; + config.Cmd = [ "${pkgs.hello}/bin/hello" ]; +} +]]></programlisting> + </para> + </section> + + <section xml:id="dockerTools-buildLayeredImage-arg-maxLayers"> + <title>Adjusting <varname>maxLayers</varname></title> + + <para> + Increasing the <varname>maxLayers</varname> increases the number of layers + which have a chance to be shared between different images. + </para> + + <para> + Modern Docker installations support up to 128 layers, however older + versions support as few as 42. + </para> + + <para> + If the produced image will not be extended by other Docker builds, it is + safe to set <varname>maxLayers</varname> to <literal>128</literal>. However + it will be impossible to extend the image further. + </para> + + <para> + The first (<literal>maxLayers-2</literal>) most "popular" paths will have + their own individual layers, then layer #<literal>maxLayers-1</literal> + will contain all the remaining "unpopular" paths, and finally layer + #<literal>maxLayers</literal> will contain the Image configuration. + </para> + + <para> + Docker's Layers are not inherently ordered, they are content-addressable + and are not explicitly layered until they are composed in to an Image. + </para> + </section> + </section> + + <section xml:id="ssec-pkgs-dockerTools-fetchFromRegistry"> + <title>pullImage</title> + + <para> + This function is analogous to the <command>docker pull</command> command, in + that can be used to pull a Docker image from a Docker registry. By default + <link xlink:href="https://hub.docker.com/">Docker Hub</link> is used to pull + images. + </para> + + <para> + Its parameters are described in the example below: + </para> + + <example xml:id='ex-dockerTools-pullImage'> + <title>Docker pull</title> +<programlisting> +pullImage { + imageName = "nixos/nix"; <co xml:id='ex-dockerTools-pullImage-1' /> + imageDigest = "sha256:20d9485b25ecfd89204e843a962c1bd70e9cc6858d65d7f5fadc340246e2116b"; <co xml:id='ex-dockerTools-pullImage-2' /> + finalImageTag = "1.11"; <co xml:id='ex-dockerTools-pullImage-3' /> + sha256 = "0mqjy3zq2v6rrhizgb9nvhczl87lcfphq9601wcprdika2jz7qh8"; <co xml:id='ex-dockerTools-pullImage-4' /> + os = "linux"; <co xml:id='ex-dockerTools-pullImage-5' /> + arch = "x86_64"; <co xml:id='ex-dockerTools-pullImage-6' /> +} +</programlisting> + </example> + + <calloutlist> + <callout arearefs='ex-dockerTools-pullImage-1'> + <para> + <varname>imageName</varname> specifies the name of the image to be + downloaded, which can also include the registry namespace (e.g. + <literal>nixos</literal>). This argument is required. + </para> + </callout> + <callout arearefs='ex-dockerTools-pullImage-2'> + <para> + <varname>imageDigest</varname> specifies the digest of the image to be + downloaded. Skopeo can be used to get the digest of an image, with its + <varname>inspect</varname> subcommand. Since a given + <varname>imageName</varname> may transparently refer to a manifest list of + images which support multiple architectures and/or operating systems, + supply the `--override-os` and `--override-arch` arguments to specify + exactly which image you want. By default it will match the OS and + architecture of the host the command is run on. +<programlisting> +$ nix-shell --packages skopeo jq --command "skopeo --override-os linux --override-arch x86_64 inspect docker://docker.io/nixos/nix:1.11 | jq -r '.Digest'" +sha256:20d9485b25ecfd89204e843a962c1bd70e9cc6858d65d7f5fadc340246e2116b +</programlisting> + This argument is required. + </para> + </callout> + <callout arearefs='ex-dockerTools-pullImage-3'> + <para> + <varname>finalImageTag</varname>, if specified, this is the tag of the + image to be created. Note it is never used to fetch the image since we + prefer to rely on the immutable digest ID. By default it's + <literal>latest</literal>. + </para> + </callout> + <callout arearefs='ex-dockerTools-pullImage-4'> + <para> + <varname>sha256</varname> is the checksum of the whole fetched image. This + argument is required. + </para> + </callout> + <callout arearefs='ex-dockerTools-pullImage-5'> + <para> + <varname>os</varname>, if specified, is the operating system of the + fetched image. By default it's <literal>linux</literal>. + </para> + </callout> + <callout arearefs='ex-dockerTools-pullImage-6'> + <para> + <varname>arch</varname>, if specified, is the cpu architecture of the + fetched image. By default it's <literal>x86_64</literal>. + </para> + </callout> + </calloutlist> + </section> + + <section xml:id="ssec-pkgs-dockerTools-exportImage"> + <title>exportImage</title> + + <para> + This function is analogous to the <command>docker export</command> command, + in that can used to flatten a Docker image that contains multiple layers. It + is in fact the result of the merge of all the layers of the image. As such, + the result is suitable for being imported in Docker with <command>docker + import</command>. + </para> + + <note> + <para> + Using this function requires the <literal>kvm</literal> device to be + available. + </para> + </note> + + <para> + The parameters of <varname>exportImage</varname> are the following: + </para> + + <example xml:id='ex-dockerTools-exportImage'> + <title>Docker export</title> +<programlisting> +exportImage { + fromImage = someLayeredImage; + fromImageName = null; + fromImageTag = null; + + name = someLayeredImage.name; +} + </programlisting> + </example> + + <para> + The parameters relative to the base image have the same synopsis as + described in <xref linkend='ssec-pkgs-dockerTools-buildImage'/>, except that + <varname>fromImage</varname> is the only required argument in this case. + </para> + + <para> + The <varname>name</varname> argument is the name of the derivation output, + which defaults to <varname>fromImage.name</varname>. + </para> + </section> + + <section xml:id="ssec-pkgs-dockerTools-shadowSetup"> + <title>shadowSetup</title> + + <para> + This constant string is a helper for setting up the base files for managing + users and groups, only if such files don't exist already. It is suitable for + being used in a <varname>runAsRoot</varname> + <xref linkend='ex-dockerTools-buildImage-runAsRoot'/> script for cases like + in the example below: + </para> + + <example xml:id='ex-dockerTools-shadowSetup'> + <title>Shadow base files</title> +<programlisting> +buildImage { + name = "shadow-basic"; + + runAsRoot = '' + #!${stdenv.shell} + ${shadowSetup} + groupadd -r redis + useradd -r -g redis redis + mkdir /data + chown redis:redis /data + ''; +} +</programlisting> + </example> + + <para> + Creating base files like <literal>/etc/passwd</literal> or + <literal>/etc/login.defs</literal> are necessary for shadow-utils to + manipulate users and groups. + </para> + </section> +</section> diff --git a/nixpkgs/doc/functions/fhs-environments.xml b/nixpkgs/doc/functions/fhs-environments.xml new file mode 100644 index 000000000000..79682080be31 --- /dev/null +++ b/nixpkgs/doc/functions/fhs-environments.xml @@ -0,0 +1,142 @@ +<section xmlns="http://docbook.org/ns/docbook" + xmlns:xlink="http://www.w3.org/1999/xlink" + xmlns:xi="http://www.w3.org/2001/XInclude" + xml:id="sec-fhs-environments"> + <title>buildFHSUserEnv</title> + + <para> + <function>buildFHSUserEnv</function> provides a way to build and run + FHS-compatible lightweight sandboxes. It creates an isolated root with bound + <filename>/nix/store</filename>, so its footprint in terms of disk space + needed is quite small. This allows one to run software which is hard or + unfeasible to patch for NixOS -- 3rd-party source trees with FHS assumptions, + games distributed as tarballs, software with integrity checking and/or + external self-updated binaries. It uses Linux namespaces feature to create + temporary lightweight environments which are destroyed after all child + processes exit, without root user rights requirement. Accepted arguments are: + </para> + + <variablelist> + <varlistentry> + <term> + <literal>name</literal> + </term> + <listitem> + <para> + Environment name. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <literal>targetPkgs</literal> + </term> + <listitem> + <para> + Packages to be installed for the main host's architecture (i.e. x86_64 on + x86_64 installations). Along with libraries binaries are also installed. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <literal>multiPkgs</literal> + </term> + <listitem> + <para> + Packages to be installed for all architectures supported by a host (i.e. + i686 and x86_64 on x86_64 installations). Only libraries are installed by + default. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <literal>extraBuildCommands</literal> + </term> + <listitem> + <para> + Additional commands to be executed for finalizing the directory structure. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <literal>extraBuildCommandsMulti</literal> + </term> + <listitem> + <para> + Like <literal>extraBuildCommands</literal>, but executed only on multilib + architectures. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <literal>extraOutputsToInstall</literal> + </term> + <listitem> + <para> + Additional derivation outputs to be linked for both target and + multi-architecture packages. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <literal>extraInstallCommands</literal> + </term> + <listitem> + <para> + Additional commands to be executed for finalizing the derivation with + runner script. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <literal>runScript</literal> + </term> + <listitem> + <para> + A command that would be executed inside the sandbox and passed all the + command line arguments. It defaults to <literal>bash</literal>. + </para> + </listitem> + </varlistentry> + </variablelist> + + <para> + One can create a simple environment using a <literal>shell.nix</literal> like + that: + </para> + +<programlisting><![CDATA[ +{ pkgs ? import <nixpkgs> {} }: + +(pkgs.buildFHSUserEnv { + name = "simple-x11-env"; + targetPkgs = pkgs: (with pkgs; + [ udev + alsaLib + ]) ++ (with pkgs.xorg; + [ libX11 + libXcursor + libXrandr + ]); + multiPkgs = pkgs: (with pkgs; + [ udev + alsaLib + ]); + runScript = "bash"; +}).env +]]></programlisting> + + <para> + Running <literal>nix-shell</literal> would then drop you into a shell with + these libraries and binaries available. You can use this to run closed-source + applications which expect FHS structure without hassles: simply change + <literal>runScript</literal> to the application path, e.g. + <filename>./bin/start.sh</filename> -- relative paths are supported. + </para> +</section> diff --git a/nixpkgs/doc/functions/generators.xml b/nixpkgs/doc/functions/generators.xml new file mode 100644 index 000000000000..e860b10e8979 --- /dev/null +++ b/nixpkgs/doc/functions/generators.xml @@ -0,0 +1,89 @@ +<section xmlns="http://docbook.org/ns/docbook" + xmlns:xlink="http://www.w3.org/1999/xlink" + xmlns:xi="http://www.w3.org/2001/XInclude" + xml:id="sec-generators"> + <title>Generators</title> + + <para> + Generators are functions that create file formats from nix data structures, + e. g. for configuration files. There are generators available for: + <literal>INI</literal>, <literal>JSON</literal> and <literal>YAML</literal> + </para> + + <para> + All generators follow a similar call interface: <code>generatorName + configFunctions data</code>, where <literal>configFunctions</literal> is an + attrset of user-defined functions that format nested parts of the content. + They each have common defaults, so often they do not need to be set manually. + An example is <code>mkSectionName ? (name: libStr.escape [ "[" "]" ] + name)</code> from the <literal>INI</literal> generator. It receives the name + of a section and sanitizes it. The default <literal>mkSectionName</literal> + escapes <literal>[</literal> and <literal>]</literal> with a backslash. + </para> + + <para> + Generators can be fine-tuned to produce exactly the file format required by + your application/service. One example is an INI-file format which uses + <literal>: </literal> as separator, the strings + <literal>"yes"</literal>/<literal>"no"</literal> as boolean values and + requires all string values to be quoted: + </para> + +<programlisting> +with lib; +let + customToINI = generators.toINI { + # specifies how to format a key/value pair + mkKeyValue = generators.mkKeyValueDefault { + # specifies the generated string for a subset of nix values + mkValueString = v: + if v == true then ''"yes"'' + else if v == false then ''"no"'' + else if isString v then ''"${v}"'' + # and delegats all other values to the default generator + else generators.mkValueStringDefault {} v; + } ":"; + }; + +# the INI file can now be given as plain old nix values +in customToINI { + main = { + pushinfo = true; + autopush = false; + host = "localhost"; + port = 42; + }; + mergetool = { + merge = "diff3"; + }; +} +</programlisting> + + <para> + This will produce the following INI file as nix string: + </para> + +<programlisting> +[main] +autopush:"no" +host:"localhost" +port:42 +pushinfo:"yes" +str\:ange:"very::strange" + +[mergetool] +merge:"diff3" +</programlisting> + + <note> + <para> + Nix store paths can be converted to strings by enclosing a derivation + attribute like so: <code>"${drv}"</code>. + </para> + </note> + + <para> + Detailed documentation for each generator can be found in + <literal>lib/generators.nix</literal>. + </para> +</section> diff --git a/nixpkgs/doc/functions/library.xml b/nixpkgs/doc/functions/library.xml new file mode 100644 index 000000000000..901423c52a18 --- /dev/null +++ b/nixpkgs/doc/functions/library.xml @@ -0,0 +1,15 @@ +<section xmlns="http://docbook.org/ns/docbook" + xmlns:xlink="http://www.w3.org/1999/xlink" + xmlns:xi="http://www.w3.org/2001/XInclude" + xml:id="sec-functions-library"> + <title>Nixpkgs Library Functions</title> + + <para> + Nixpkgs provides a standard library at <varname>pkgs.lib</varname>, or + through <code>import <nixpkgs/lib></code>. + </para> + + <xi:include href="./library/asserts.xml" /> + + <xi:include href="./library/attrsets.xml" /> +</section> diff --git a/nixpkgs/doc/functions/library/asserts.xml b/nixpkgs/doc/functions/library/asserts.xml new file mode 100644 index 000000000000..437850e408bc --- /dev/null +++ b/nixpkgs/doc/functions/library/asserts.xml @@ -0,0 +1,117 @@ +<section xmlns="http://docbook.org/ns/docbook" + xmlns:xlink="http://www.w3.org/1999/xlink" + xmlns:xi="http://www.w3.org/2001/XInclude" + xml:id="sec-functions-library-asserts"> + <title>Assert functions</title> + + <section xml:id="function-library-lib.asserts.assertMsg"> + <title><function>lib.asserts.assertMsg</function></title> + + <subtitle><literal>assertMsg :: Bool -> String -> Bool</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.asserts.assertMsg" /> + + <para> + Print a trace message if <literal>pred</literal> is false. + </para> + + <para> + Intended to be used to augment asserts with helpful error messages. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>pred</varname> + </term> + <listitem> + <para> + Condition under which the <varname>msg</varname> should + <emphasis>not</emphasis> be printed. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>msg</varname> + </term> + <listitem> + <para> + Message to print. + </para> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.asserts.assertMsg-example-false"> + <title>Printing when the predicate is false</title> +<programlisting><![CDATA[ +assert lib.asserts.assertMsg ("foo" == "bar") "foo is not bar, silly" +stderr> trace: foo is not bar, silly +stderr> assert failed +]]></programlisting> + </example> + </section> + + <section xml:id="function-library-lib.asserts.assertOneOf"> + <title><function>lib.asserts.assertOneOf</function></title> + + <subtitle><literal>assertOneOf :: String -> String -> + StringList -> Bool</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.asserts.assertOneOf" /> + + <para> + Specialized <function>asserts.assertMsg</function> for checking if + <varname>val</varname> is one of the elements of <varname>xs</varname>. + Useful for checking enums. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>name</varname> + </term> + <listitem> + <para> + The name of the variable the user entered <varname>val</varname> into, + for inclusion in the error message. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>val</varname> + </term> + <listitem> + <para> + The value of what the user provided, to be compared against the values in + <varname>xs</varname>. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>xs</varname> + </term> + <listitem> + <para> + The list of valid values. + </para> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.asserts.assertOneOf-example"> + <title>Ensuring a user provided a possible value</title> +<programlisting><![CDATA[ +let sslLibrary = "bearssl"; +in lib.asserts.assertOneOf "sslLibrary" sslLibrary [ "openssl" "bearssl" ]; +=> false +stderr> trace: sslLibrary must be one of "openssl", "libressl", but is: "bearssl" + ]]></programlisting> + </example> + </section> +</section> diff --git a/nixpkgs/doc/functions/library/attrsets.xml b/nixpkgs/doc/functions/library/attrsets.xml new file mode 100644 index 000000000000..65d0b40e2e82 --- /dev/null +++ b/nixpkgs/doc/functions/library/attrsets.xml @@ -0,0 +1,1731 @@ +<section xmlns="http://docbook.org/ns/docbook" + xmlns:xlink="http://www.w3.org/1999/xlink" + xmlns:xi="http://www.w3.org/2001/XInclude" + xml:id="sec-functions-library-attrset"> + <title>Attribute-Set Functions</title> + + <section xml:id="function-library-lib.attrsets.attrByPath"> + <title><function>lib.attrset.attrByPath</function></title> + + <subtitle><literal>attrByPath :: [String] -> Any -> AttrSet</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.attrByPath" /> + + <para> + Return an attribute from within nested attribute sets. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>attrPath</varname> + </term> + <listitem> + <para> + A list of strings representing the path through the nested attribute set + <varname>set</varname>. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>default</varname> + </term> + <listitem> + <para> + Default value if <varname>attrPath</varname> does not resolve to an + existing value. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>set</varname> + </term> + <listitem> + <para> + The nested attributeset to select values from. + </para> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.attrset.attrByPath-example-value-exists"> + <title>Extracting a value from a nested attribute set</title> +<programlisting><![CDATA[ +let set = { a = { b = 3; }; }; +in lib.attrsets.attrByPath [ "a" "b" ] 0 set +=> 3 +]]></programlisting> + </example> + + <example xml:id="function-library-lib.attrset.attrByPath-example-default-value"> + <title>No value at the path, instead using the default</title> +<programlisting><![CDATA[ +lib.attrsets.attrByPath [ "a" "b" ] 0 {} +=> 0 +]]></programlisting> + </example> + </section> + + <section xml:id="function-library-lib.attrsets.hasAttrByPath"> + <title><function>lib.attrsets.hasAttrByPath</function></title> + + <subtitle><literal>hasAttrByPath :: [String] -> AttrSet -> Bool</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.hasAttrByPath" /> + + <para> + Determine if an attribute exists within a nested attribute set. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>attrPath</varname> + </term> + <listitem> + <para> + A list of strings representing the path through the nested attribute set + <varname>set</varname>. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>set</varname> + </term> + <listitem> + <para> + The nested attributeset to check. + </para> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.attrsets.hasAttrByPath-example"> + <title>A nested value does exist inside a set</title> +<programlisting><![CDATA[ +lib.attrsets.hasAttrByPath + [ "a" "b" "c" "d" ] + { a = { b = { c = { d = 123; }; }; }; } +=> true +]]></programlisting> + </example> + </section> + + <section xml:id="function-library-lib.attrsets.setAttrByPath"> + <title><function>lib.attrsets.setAttrByPath</function></title> + + <subtitle><literal>setAttrByPath :: [String] -> Any -> AttrSet</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.setAttrByPath" /> + + <para> + Create a new attribute set with <varname>value</varname> set at the nested + attribute location specified in <varname>attrPath</varname>. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>attrPath</varname> + </term> + <listitem> + <para> + A list of strings representing the path through the nested attribute set. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>value</varname> + </term> + <listitem> + <para> + The value to set at the location described by + <varname>attrPath</varname>. + </para> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.attrsets.setAttrByPath-example"> + <title>Creating a new nested attribute set</title> +<programlisting><![CDATA[ +lib.attrsets.setAttrByPath [ "a" "b" ] 3 +=> { a = { b = 3; }; } +]]></programlisting> + </example> + </section> + + <section xml:id="function-library-lib.attrsets.getAttrFromPath"> + <title><function>lib.attrsets.getAttrFromPath</function></title> + + <subtitle><literal>getAttrFromPath :: [String] -> AttrSet -> Value</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.getAttrFromPath" /> + + <para> + Like <xref linkend="function-library-lib.attrsets.attrByPath" /> except + without a default, and it will throw if the value doesn't exist. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>attrPath</varname> + </term> + <listitem> + <para> + A list of strings representing the path through the nested attribute set + <varname>set</varname>. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>set</varname> + </term> + <listitem> + <para> + The nested attribute set to find the value in. + </para> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.attrsets.getAttrPath-example-success"> + <title>Succesfully getting a value from an attribute set</title> +<programlisting><![CDATA[ +lib.attrsets.getAttrFromPath [ "a" "b" ] { a = { b = 3; }; } +=> 3 +]]></programlisting> + </example> + + <example xml:id="function-library-lib.attrsets.getAttrPath-example-throw"> + <title>Throwing after failing to get a value from an attribute set</title> +<programlisting><![CDATA[ +lib.attrsets.getAttrFromPath [ "x" "y" ] { } +=> error: cannot find attribute `x.y' +]]></programlisting> + </example> + </section> + + <section xml:id="function-library-lib.attrsets.attrVals"> + <title><function>lib.attrsets.attrVals</function></title> + + <subtitle><literal>attrVals :: [String] -> AttrSet -> [Any]</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.attrVals" /> + + <para> + Return the specified attributes from a set. All values must exist. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>nameList</varname> + </term> + <listitem> + <para> + The list of attributes to fetch from <varname>set</varname>. Each + attribute name must exist on the attrbitue set. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>set</varname> + </term> + <listitem> + <para> + The set to get attribute values from. + </para> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.attrsets.attrVals-example-success"> + <title>Getting several values from an attribute set</title> +<programlisting><![CDATA[ +lib.attrsets.attrVals [ "a" "b" "c" ] { a = 1; b = 2; c = 3; } +=> [ 1 2 3 ] +]]></programlisting> + </example> + + <example xml:id="function-library-lib.attrsets.attrVals-failure"> + <title>Getting missing values from an attribute set</title> +<programlisting><![CDATA[ +lib.attrsets.attrVals [ "d" ] { } +error: attribute 'd' missing +]]></programlisting> + </example> + </section> + + <section xml:id="function-library-lib.attrsets.attrValues"> + <title><function>lib.attrsets.attrValues</function></title> + + <subtitle><literal>attrValues :: AttrSet -> [Any]</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.attrValues" /> + + <para> + Get all the attribute values from an attribute set. + </para> + + <para> + Provides a backwards-compatible interface of + <function>builtins.attrValues</function> for Nix version older than 1.8. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>attrs</varname> + </term> + <listitem> + <para> + The attribute set. + </para> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.attrsets.attrValues-example"> + <title></title> +<programlisting><![CDATA[ +lib.attrsets.attrValues { a = 1; b = 2; c = 3; } +=> [ 1 2 3 ] +]]></programlisting> + </example> + </section> + + <section xml:id="function-library-lib.attrsets.catAttrs"> + <title><function>lib.attrsets.catAttrs</function></title> + + <subtitle><literal>catAttrs :: String -> AttrSet -> [Any]</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.catAttrs" /> + + <para> + Collect each attribute named `attr' from the list of attribute sets, + <varname>sets</varname>. Sets that don't contain the named attribute are + ignored. + </para> + + <para> + Provides a backwards-compatible interface of + <function>builtins.catAttrs</function> for Nix version older than 1.9. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>attr</varname> + </term> + <listitem> + <para> + Attribute name to select from each attribute set in + <varname>sets</varname>. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>sets</varname> + </term> + <listitem> + <para> + The list of attribute sets to select <varname>attr</varname> from. + </para> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.attrsets.catAttrs-example"> + <title>Collect an attribute from a list of attribute sets.</title> + <para> + Attribute sets which don't have the attribute are ignored. + </para> +<programlisting><![CDATA[ +catAttrs "a" [{a = 1;} {b = 0;} {a = 2;}] +=> [ 1 2 ] + ]]></programlisting> + </example> + </section> + + <section xml:id="function-library-lib.attrsets.filterAttrs"> + <title><function>lib.attrsets.filterAttrs</function></title> + + <subtitle><literal>filterAttrs :: (String -> Any -> Bool) -> AttrSet -> AttrSet</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.filterAttrs" /> + + <para> + Filter an attribute set by removing all attributes for which the given + predicate return false. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>pred</varname> + </term> + <listitem> + <para> + <literal>String -> Any -> Bool</literal> + </para> + <para> + Predicate which returns true to include an attribute, or returns false to + exclude it. + </para> + <variablelist> + <varlistentry> + <term> + <varname>name</varname> + </term> + <listitem> + <para> + The attribute's name + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>value</varname> + </term> + <listitem> + <para> + The attribute's value + </para> + </listitem> + </varlistentry> + </variablelist> + <para> + Returns <literal>true</literal> to include the attribute, + <literal>false</literal> to exclude the attribute. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>set</varname> + </term> + <listitem> + <para> + The attribute set to filter + </para> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.attrsets.filterAttrs-example"> + <title>Filtering an attributeset</title> +<programlisting><![CDATA[ +filterAttrs (n: v: n == "foo") { foo = 1; bar = 2; } +=> { foo = 1; } +]]></programlisting> + </example> + </section> + + <section xml:id="function-library-lib.attrsets.filterAttrsRecursive"> + <title><function>lib.attrsets.filterAttrsRecursive</function></title> + + <subtitle><literal>filterAttrsRecursive :: (String -> Any -> Bool) -> AttrSet -> AttrSet</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.filterAttrsRecursive" /> + + <para> + Filter an attribute set recursively by removing all attributes for which the + given predicate return false. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>pred</varname> + </term> + <listitem> + <para> + <literal>String -> Any -> Bool</literal> + </para> + <para> + Predicate which returns true to include an attribute, or returns false to + exclude it. + </para> + <variablelist> + <varlistentry> + <term> + <varname>name</varname> + </term> + <listitem> + <para> + The attribute's name + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>value</varname> + </term> + <listitem> + <para> + The attribute's value + </para> + </listitem> + </varlistentry> + </variablelist> + <para> + Returns <literal>true</literal> to include the attribute, + <literal>false</literal> to exclude the attribute. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>set</varname> + </term> + <listitem> + <para> + The attribute set to filter + </para> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.attrsets.filterAttrsRecursive-example"> + <title>Recursively filtering an attribute set</title> +<programlisting><![CDATA[ +lib.attrsets.filterAttrsRecursive + (n: v: v != null) + { + levelA = { + example = "hi"; + levelB = { + hello = "there"; + this-one-is-present = { + this-is-excluded = null; + }; + }; + this-one-is-also-excluded = null; + }; + also-excluded = null; + } +=> { + levelA = { + example = "hi"; + levelB = { + hello = "there"; + this-one-is-present = { }; + }; + }; + } + ]]></programlisting> + </example> + </section> + + <section xml:id="function-library-lib.attrsets.foldAttrs"> + <title><function>lib.attrsets.foldAttrs</function></title> + + <subtitle><literal>foldAttrs :: (Any -> Any -> Any) -> Any -> [AttrSets] -> Any</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.foldAttrs" /> + + <para> + Apply fold function to values grouped by key. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>op</varname> + </term> + <listitem> + <para> + <literal>Any -> Any -> Any</literal> + </para> + <para> + Given a value <varname>val</varname> and a collector + <varname>col</varname>, combine the two. + </para> + <variablelist> + <varlistentry> + <term> + <varname>val</varname> + </term> + <listitem> + <para> + An attribute's value + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>col</varname> + </term> + <listitem> +<!-- TODO: make this not bad, use more fold-ey terms --> + <para> + The result of previous <function>op</function> calls with other values + and <function>nul</function>. + </para> + </listitem> + </varlistentry> + </variablelist> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>nul</varname> + </term> + <listitem> + <para> + The null-value, the starting value. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>list_of_attrs</varname> + </term> + <listitem> + <para> + A list of attribute sets to fold together by key. + </para> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.attrsets.foldAttrs-example"> + <title>Combining an attribute of lists in to one attribute set</title> +<programlisting><![CDATA[ +lib.attrsets.foldAttrs + (n: a: [n] ++ a) [] + [ + { a = 2; b = 7; } + { a = 3; } + { b = 6; } + ] +=> { a = [ 2 3 ]; b = [ 7 6 ]; } +]]></programlisting> + </example> + </section> + + <section xml:id="function-library-lib.attrsets.collect"> + <title><function>lib.attrsets.collect</function></title> + + <subtitle><literal>collect :: (Any -> Bool) -> AttrSet -> [Any]</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.collect" /> + + <para> + Recursively collect sets that verify a given predicate named + <varname>pred</varname> from the set <varname>attrs</varname>. The recursion + stops when <varname>pred</varname> returns <literal>true</literal>. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>pred</varname> + </term> + <listitem> + <para> + <literal>Any -> Bool</literal> + </para> + <para> + Given an attribute's value, determine if recursion should stop. + </para> + <variablelist> + <varlistentry> + <term> + <varname>value</varname> + </term> + <listitem> + <para> + The attribute set value. + </para> + </listitem> + </varlistentry> + </variablelist> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>attrs</varname> + </term> + <listitem> + <para> + The attribute set to recursively collect. + </para> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.attrsets.collect-example-lists"> + <title>Collecting all lists from an attribute set</title> +<programlisting><![CDATA[ +lib.attrsets.collect isList { a = { b = ["b"]; }; c = [1]; } +=> [["b"] [1]] +]]></programlisting> + </example> + + <example xml:id="function-library-lib.attrsets.collect-example-outpath"> + <title>Collecting all attribute-sets which contain the <literal>outPath</literal> attribute name.</title> +<programlisting><![CDATA[ +collect (x: x ? outPath) + { a = { outPath = "a/"; }; b = { outPath = "b/"; }; } +=> [{ outPath = "a/"; } { outPath = "b/"; }] +]]></programlisting> + </example> + </section> + + <section xml:id="function-library-lib.attrsets.nameValuePair"> + <title><function>lib.attrsets.nameValuePair</function></title> + + <subtitle><literal>nameValuePair :: String -> Any -> AttrSet</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.nameValuePair" /> + + <para> + Utility function that creates a <literal>{name, value}</literal> pair as + expected by <function>builtins.listToAttrs</function>. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>name</varname> + </term> + <listitem> + <para> + The attribute name. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>value</varname> + </term> + <listitem> + <para> + The attribute value. + </para> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.attrsets.nameValuePair-example"> + <title>Creating a name value pair</title> +<programlisting><![CDATA[ +nameValuePair "some" 6 +=> { name = "some"; value = 6; } +]]></programlisting> + </example> + </section> + + <section xml:id="function-library-lib.attrsets.mapAttrs"> + <title><function>lib.attrsets.mapAttrs</function></title> + + <subtitle><literal></literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.mapAttrs" /> + + <para> + Apply a function to each element in an attribute set, creating a new + attribute set. + </para> + + <para> + Provides a backwards-compatible interface of + <function>builtins.mapAttrs</function> for Nix version older than 2.1. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>fn</varname> + </term> + <listitem> + <para> + <literal>String -> Any -> Any</literal> + </para> + <para> + Given an attribute's name and value, return a new value. + </para> + <variablelist> + <varlistentry> + <term> + <varname>name</varname> + </term> + <listitem> + <para> + The name of the attribute. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>value</varname> + </term> + <listitem> + <para> + The attribute's value. + </para> + </listitem> + </varlistentry> + </variablelist> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.attrsets.mapAttrs-example"> + <title>Modifying each value of an attribute set</title> +<programlisting><![CDATA[ +lib.attrsets.mapAttrs + (name: value: name + "-" value) + { x = "foo"; y = "bar"; } +=> { x = "x-foo"; y = "y-bar"; } +]]></programlisting> + </example> + </section> + + <section xml:id="function-library-lib.attrsets.mapAttrs-prime"> + <title><function>lib.attrsets.mapAttrs'</function></title> + + <subtitle><literal>mapAttrs' :: (String -> Any -> { name = String; value = Any }) -> AttrSet -> AttrSet</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.mapAttrs-prime" /> + + <para> + Like <function>mapAttrs</function>, but allows the name of each attribute to + be changed in addition to the value. The applied function should return both + the new name and value as a <function>nameValuePair</function>. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>fn</varname> + </term> + <listitem> + <para> + <literal>String -> Any -> { name = String; value = Any }</literal> + </para> + <para> + Given an attribute's name and value, return a new + <link + linkend="function-library-lib.attrsets.nameValuePair">name + value pair</link>. + </para> + <variablelist> + <varlistentry> + <term> + <varname>name</varname> + </term> + <listitem> + <para> + The name of the attribute. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>value</varname> + </term> + <listitem> + <para> + The attribute's value. + </para> + </listitem> + </varlistentry> + </variablelist> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>set</varname> + </term> + <listitem> + <para> + The attribute set to map over. + </para> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.attrsets.mapAttrs-prime-example"> + <title>Change the name and value of each attribute of an attribute set</title> +<programlisting><![CDATA[ +lib.attrsets.mapAttrs' (name: value: lib.attrsets.nameValuePair ("foo_" + name) ("bar-" + value)) + { x = "a"; y = "b"; } +=> { foo_x = "bar-a"; foo_y = "bar-b"; } + + ]]></programlisting> + </example> + </section> + + <section xml:id="function-library-lib.attrsets.mapAttrsToList"> + <title><function>lib.attrsets.mapAttrsToList</function></title> + + <subtitle><literal>mapAttrsToList :: (String -> Any -> Any) -> + AttrSet -> Any</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.mapAttrsToList" /> + + <para> + Call <varname>fn</varname> for each attribute in the given + <varname>set</varname> and return the result in a list. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>fn</varname> + </term> + <listitem> + <para> + <literal>String -> Any -> Any</literal> + </para> + <para> + Given an attribute's name and value, return a new value. + </para> + <variablelist> + <varlistentry> + <term> + <varname>name</varname> + </term> + <listitem> + <para> + The name of the attribute. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>value</varname> + </term> + <listitem> + <para> + The attribute's value. + </para> + </listitem> + </varlistentry> + </variablelist> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>set</varname> + </term> + <listitem> + <para> + The attribute set to map over. + </para> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.attrsets.mapAttrsToList-example"> + <title>Combine attribute values and names in to a list</title> +<programlisting><![CDATA[ +lib.attrsets.mapAttrsToList (name: value: "${name}=${value}") + { x = "a"; y = "b"; } +=> [ "x=a" "y=b" ] +]]></programlisting> + </example> + </section> + + <section xml:id="function-library-lib.attrsets.mapAttrsRecursive"> + <title><function>lib.attrsets.mapAttrsRecursive</function></title> + + <subtitle><literal>mapAttrsRecursive :: ([String] > Any -> Any) -> AttrSet -> AttrSet</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.mapAttrsRecursive" /> + + <para> + Like <function>mapAttrs</function>, except that it recursively applies + itself to attribute sets. Also, the first argument of the argument function + is a <emphasis>list</emphasis> of the names of the containing attributes. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>f</varname> + </term> + <listitem> + <para> + <literal>[ String ] -> Any -> Any</literal> + </para> + <para> + Given a list of attribute names and value, return a new value. + </para> + <variablelist> + <varlistentry> + <term> + <varname>name_path</varname> + </term> + <listitem> + <para> + The list of attribute names to this value. + </para> + <para> + For example, the <varname>name_path</varname> for the + <literal>example</literal> string in the attribute set <literal>{ foo + = { bar = "example"; }; }</literal> is <literal>[ "foo" "bar" + ]</literal>. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>value</varname> + </term> + <listitem> + <para> + The attribute's value. + </para> + </listitem> + </varlistentry> + </variablelist> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>set</varname> + </term> + <listitem> + <para> + The attribute set to recursively map over. + </para> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.attrsets.mapAttrsRecursive-example"> + <title>A contrived example of using <function>lib.attrsets.mapAttrsRecursive</function></title> +<programlisting><![CDATA[ +mapAttrsRecursive + (path: value: concatStringsSep "-" (path ++ [value])) + { + n = { + a = "A"; + m = { + b = "B"; + c = "C"; + }; + }; + d = "D"; + } +=> { + n = { + a = "n-a-A"; + m = { + b = "n-m-b-B"; + c = "n-m-c-C"; + }; + }; + d = "d-D"; + } + ]]></programlisting> + </example> + </section> + + <section xml:id="function-library-lib.attrsets.mapAttrsRecursiveCond"> + <title><function>lib.attrsets.mapAttrsRecursiveCond</function></title> + + <subtitle><literal>mapAttrsRecursiveCond :: (AttrSet -> Bool) -> ([ String ] -> Any -> Any) -> AttrSet -> AttrSet</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.mapAttrsRecursiveCond" /> + + <para> + Like <function>mapAttrsRecursive</function>, but it takes an additional + predicate function that tells it whether to recursive into an attribute set. + If it returns false, <function>mapAttrsRecursiveCond</function> does not + recurse, but does apply the map function. It is returns true, it does + recurse, and does not apply the map function. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>cond</varname> + </term> + <listitem> + <para> + <literal>(AttrSet -> Bool)</literal> + </para> + <para> + Determine if <function>mapAttrsRecursive</function> should recurse deeper + in to the attribute set. + </para> + <variablelist> + <varlistentry> + <term> + <varname>attributeset</varname> + </term> + <listitem> + <para> + An attribute set. + </para> + </listitem> + </varlistentry> + </variablelist> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>f</varname> + </term> + <listitem> + <para> + <literal>[ String ] -> Any -> Any</literal> + </para> + <para> + Given a list of attribute names and value, return a new value. + </para> + <variablelist> + <varlistentry> + <term> + <varname>name_path</varname> + </term> + <listitem> + <para> + The list of attribute names to this value. + </para> + <para> + For example, the <varname>name_path</varname> for the + <literal>example</literal> string in the attribute set <literal>{ foo + = { bar = "example"; }; }</literal> is <literal>[ "foo" "bar" + ]</literal>. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>value</varname> + </term> + <listitem> + <para> + The attribute's value. + </para> + </listitem> + </varlistentry> + </variablelist> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>set</varname> + </term> + <listitem> + <para> + The attribute set to recursively map over. + </para> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.attrsets.mapAttrsRecursiveCond-example"> + <title>Only convert attribute values to JSON if the containing attribute set is marked for recursion</title> +<programlisting><![CDATA[ +lib.attrsets.mapAttrsRecursiveCond + ({ recurse ? false, ... }: recurse) + (name: value: builtins.toJSON value) + { + dorecur = { + recurse = true; + hello = "there"; + }; + dontrecur = { + converted-to- = "json"; + }; + } +=> { + dorecur = { + hello = "\"there\""; + recurse = "true"; + }; + dontrecur = "{\"converted-to\":\"json\"}"; + } + ]]></programlisting> + </example> + </section> + + <section xml:id="function-library-lib.attrsets.genAttrs"> + <title><function>lib.attrsets.genAttrs</function></title> + + <subtitle><literal>genAttrs :: [ String ] -> (String -> Any) -> AttrSet</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.genAttrs" /> + + <para> + Generate an attribute set by mapping a function over a list of attribute + names. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>names</varname> + </term> + <listitem> + <para> + Names of values in the resulting attribute set. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>f</varname> + </term> + <listitem> + <para> + <literal>String -> Any</literal> + </para> + <para> + Takes the name of the attribute and return the attribute's value. + </para> + <variablelist> + <varlistentry> + <term> + <varname>name</varname> + </term> + <listitem> + <para> + The name of the attribute to generate a value for. + </para> + </listitem> + </varlistentry> + </variablelist> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.attrsets.genAttrs-example"> + <title>Generate an attrset based on names only</title> +<programlisting><![CDATA[ +lib.attrsets.genAttrs [ "foo" "bar" ] (name: "x_${name}") +=> { foo = "x_foo"; bar = "x_bar"; } + ]]></programlisting> + </example> + </section> + + <section xml:id="function-library-lib.attrsets.isDerivation"> + <title><function>lib.attrsets.isDerivation</function></title> + + <subtitle><literal>isDerivation :: Any -> Bool</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.isDerivation" /> + + <para> + Check whether the argument is a derivation. Any set with <code>{ type = + "derivation"; }</code> counts as a derivation. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>value</varname> + </term> + <listitem> + <para> + The value which is possibly a derivation. + </para> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.attrsets.isDerivation-example-true"> + <title>A package is a derivation</title> +<programlisting><![CDATA[ +lib.attrsets.isDerivation (import <nixpkgs> {}).ruby +=> true + ]]></programlisting> + </example> + + <example xml:id="function-library-lib.attrsets.isDerivation-example-false"> + <title>Anything else is not a derivation</title> +<programlisting><![CDATA[ +lib.attrsets.isDerivation "foobar" +=> false + ]]></programlisting> + </example> + </section> + + <section xml:id="function-library-lib.attrsets.toDerivation"> + <title><function>lib.attrsets.toDerivation</function></title> + + <subtitle><literal>toDerivation :: Path -> Derivation</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.toDerivation" /> + + <para> + Converts a store path to a fake derivation. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>path</varname> + </term> + <listitem> + <para> + A store path to convert to a derivation. + </para> + </listitem> + </varlistentry> + </variablelist> + </section> + + <section xml:id="function-library-lib.attrsets.optionalAttrs"> + <title><function>lib.attrsets.optionalAttrs</function></title> + + <subtitle><literal>optionalAttrs :: Bool -> AttrSet</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.optionalAttrs" /> + + <para> + Conditionally return an attribute set or an empty attribute set. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>cond</varname> + </term> + <listitem> + <para> + Condition under which the <varname>as</varname> attribute set is + returned. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>as</varname> + </term> + <listitem> + <para> + The attribute set to return if <varname>cond</varname> is true. + </para> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.attrsets.optionalAttrs-example-true"> + <title>Return the provided attribute set when <varname>cond</varname> is true</title> +<programlisting><![CDATA[ +lib.attrsets.optionalAttrs true { my = "set"; } +=> { my = "set"; } + ]]></programlisting> + </example> + + <example xml:id="function-library-lib.attrsets.optionalAttrs-example-false"> + <title>Return an empty attribute set when <varname>cond</varname> is false</title> +<programlisting><![CDATA[ +lib.attrsets.optionalAttrs false { my = "set"; } +=> { } + ]]></programlisting> + </example> + </section> + + <section xml:id="function-library-lib.attrsets.zipAttrsWithNames"> + <title><function>lib.attrsets.zipAttrsWithNames</function></title> + + <subtitle><literal>zipAttrsWithNames :: [ String ] -> (String -> [ Any ] -> Any) -> [ AttrSet ] -> AttrSet</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.zipAttrsWithNames" /> + + <para> + Merge sets of attributes and use the function <varname>f</varname> to merge + attribute values where the attribute name is in <varname>names</varname>. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>names</varname> + </term> + <listitem> + <para> + A list of attribute names to zip. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>f</varname> + </term> + <listitem> + <para> + <literal>(String -> [ Any ] -> Any</literal> + </para> + <para> + Accepts an attribute name, all the values, and returns a combined value. + </para> + <variablelist> + <varlistentry> + <term> + <varname>name</varname> + </term> + <listitem> + <para> + The name of the attribute each value came from. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>vs</varname> + </term> + <listitem> + <para> + A list of values collected from the list of attribute sets. + </para> + </listitem> + </varlistentry> + </variablelist> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>sets</varname> + </term> + <listitem> + <para> + A list of attribute sets to zip together. + </para> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.attrsets.zipAttrsWithNames-example"> + <title>Summing a list of attribute sets of numbers</title> +<programlisting><![CDATA[ +lib.attrsets.zipAttrsWithNames + [ "a" "b" ] + (name: vals: "${name} ${toString (builtins.foldl' (a: b: a + b) 0 vals)}") + [ + { a = 1; b = 1; c = 1; } + { a = 10; } + { b = 100; } + { c = 1000; } + ] +=> { a = "a 11"; b = "b 101"; } + ]]></programlisting> + </example> + </section> + + <section xml:id="function-library-lib.attrsets.zipAttrsWith"> + <title><function>lib.attrsets.zipAttrsWith</function></title> + + <subtitle><literal>zipAttrsWith :: (String -> [ Any ] -> Any) -> [ AttrSet ] -> AttrSet</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.zipAttrsWith" /> + + <para> + Merge sets of attributes and use the function <varname>f</varname> to merge + attribute values. Similar to + <xref + linkend="function-library-lib.attrsets.zipAttrsWithNames" /> where + all key names are passed for <varname>names</varname>. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>f</varname> + </term> + <listitem> + <para> + <literal>(String -> [ Any ] -> Any</literal> + </para> + <para> + Accepts an attribute name, all the values, and returns a combined value. + </para> + <variablelist> + <varlistentry> + <term> + <varname>name</varname> + </term> + <listitem> + <para> + The name of the attribute each value came from. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>vs</varname> + </term> + <listitem> + <para> + A list of values collected from the list of attribute sets. + </para> + </listitem> + </varlistentry> + </variablelist> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>sets</varname> + </term> + <listitem> + <para> + A list of attribute sets to zip together. + </para> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.attrsets.zipAttrsWith-example"> + <title>Summing a list of attribute sets of numbers</title> +<programlisting><![CDATA[ +lib.attrsets.zipAttrsWith + (name: vals: "${name} ${toString (builtins.foldl' (a: b: a + b) 0 vals)}") + [ + { a = 1; b = 1; c = 1; } + { a = 10; } + { b = 100; } + { c = 1000; } + ] +=> { a = "a 11"; b = "b 101"; c = "c 1001"; } + ]]></programlisting> + </example> + </section> + + <section xml:id="function-library-lib.attrsets.zipAttrs"> + <title><function>lib.attrsets.zipAttrs</function></title> + + <subtitle><literal>zipAttrsWith :: [ AttrSet ] -> AttrSet</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.zipAttrs" /> + + <para> + Merge sets of attributes and combine each attribute value in to a list. + Similar to <xref linkend="function-library-lib.attrsets.zipAttrsWith" /> + where the merge function returns a list of all values. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>sets</varname> + </term> + <listitem> + <para> + A list of attribute sets to zip together. + </para> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.attrsets.zipAttrs-example"> + <title>Combining a list of attribute sets</title> +<programlisting><![CDATA[ +lib.attrsets.zipAttrs + [ + { a = 1; b = 1; c = 1; } + { a = 10; } + { b = 100; } + { c = 1000; } + ] +=> { a = [ 1 10 ]; b = [ 1 100 ]; c = [ 1 1000 ]; } + ]]></programlisting> + </example> + </section> + + <section xml:id="function-library-lib.attrsets.recursiveUpdateUntil"> + <title><function>lib.attrsets.recursiveUpdateUntil</function></title> + + <subtitle><literal>recursiveUpdateUntil :: ( [ String ] -> AttrSet -> AttrSet -> Bool ) -> AttrSet -> AttrSet -> AttrSet</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.recursiveUpdateUntil" /> + + <para> + Does the same as the update operator <literal>//</literal> except that + attributes are merged until the given predicate is verified. The predicate + should accept 3 arguments which are the path to reach the attribute, a part + of the first attribute set and a part of the second attribute set. When the + predicate is verified, the value of the first attribute set is replaced by + the value of the second attribute set. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>pred</varname> + </term> + <listitem> + <para> + <literal>[ String ] -> AttrSet -> AttrSet -> Bool</literal> + </para> + <variablelist> + <varlistentry> + <term> + <varname>path</varname> + </term> + <listitem> + <para> + The path to the values in the left and right hand sides. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>l</varname> + </term> + <listitem> + <para> + The left hand side value. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>r</varname> + </term> + <listitem> + <para> + The right hand side value. + </para> + </listitem> + </varlistentry> + </variablelist> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>lhs</varname> + </term> + <listitem> + <para> + The left hand attribute set of the merge. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>rhs</varname> + </term> + <listitem> + <para> + The right hand attribute set of the merge. + </para> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.attrsets.recursiveUpdateUntil-example"> + <title>Recursively merging two attribute sets</title> +<programlisting><![CDATA[ +lib.attrsets.recursiveUpdateUntil (path: l: r: path == ["foo"]) + { + # first attribute set + foo.bar = 1; + foo.baz = 2; + bar = 3; + } + { + #second attribute set + foo.bar = 1; + foo.quz = 2; + baz = 4; + } +=> { + foo.bar = 1; # 'foo.*' from the second set + foo.quz = 2; # + bar = 3; # 'bar' from the first set + baz = 4; # 'baz' from the second set +} + ]]></programlisting> + </example> + </section> + + <section xml:id="function-library-lib.attrsets.recursiveUpdate"> + <title><function>lib.attrsets.recursiveUpdate</function></title> + + <subtitle><literal>recursiveUpdate :: AttrSet -> AttrSet -> AttrSet</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.recursiveUpdate" /> + + <para> + A recursive variant of the update operator <literal>//</literal>. The + recursion stops when one of the attribute values is not an attribute set, in + which case the right hand side value takes precedence over the left hand + side value. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>lhs</varname> + </term> + <listitem> + <para> + The left hand attribute set of the merge. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>rhs</varname> + </term> + <listitem> + <para> + The right hand attribute set of the merge. + </para> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.attrsets.recursiveUpdate-example"> + <title>Recursively merging two attribute sets</title> +<programlisting><![CDATA[ +recursiveUpdate + { + boot.loader.grub.enable = true; + boot.loader.grub.device = "/dev/hda"; + } + { + boot.loader.grub.device = ""; + } +=> { + boot.loader.grub.enable = true; + boot.loader.grub.device = ""; +} +]]></programlisting> + </example> + </section> +</section> diff --git a/nixpkgs/doc/functions/overrides.xml b/nixpkgs/doc/functions/overrides.xml new file mode 100644 index 000000000000..1bd90d2a0c76 --- /dev/null +++ b/nixpkgs/doc/functions/overrides.xml @@ -0,0 +1,212 @@ +<section xmlns="http://docbook.org/ns/docbook" + xmlns:xlink="http://www.w3.org/1999/xlink" + xmlns:xi="http://www.w3.org/2001/XInclude" + xml:id="sec-overrides"> + <title>Overriding</title> + + <para> + Sometimes one wants to override parts of <literal>nixpkgs</literal>, e.g. + derivation attributes, the results of derivations. + </para> + + <para> + These functions are used to make changes to packages, returning only single + packages. <link xlink:href="#chap-overlays">Overlays</link>, on the other + hand, can be used to combine the overridden packages across the entire + package set of Nixpkgs. + </para> + + <section xml:id="sec-pkg-override"> + <title><pkg>.override</title> + + <para> + The function <varname>override</varname> is usually available for all the + derivations in the nixpkgs expression (<varname>pkgs</varname>). + </para> + + <para> + It is used to override the arguments passed to a function. + </para> + + <para> + Example usages: +<programlisting>pkgs.foo.override { arg1 = val1; arg2 = val2; ... }</programlisting> +<!-- TODO: move below programlisting to a new section about extending and overlays + and reference it + --> +<programlisting> +import pkgs.path { overlays = [ (self: super: { + foo = super.foo.override { barSupport = true ; }; + })]}; +</programlisting> +<programlisting> +mypkg = pkgs.callPackage ./mypkg.nix { + mydep = pkgs.mydep.override { ... }; + } +</programlisting> + </para> + + <para> + In the first example, <varname>pkgs.foo</varname> is the result of a + function call with some default arguments, usually a derivation. Using + <varname>pkgs.foo.override</varname> will call the same function with the + given new arguments. + </para> + </section> + + <section xml:id="sec-pkg-overrideAttrs"> + <title><pkg>.overrideAttrs</title> + + <para> + The function <varname>overrideAttrs</varname> allows overriding the + attribute set passed to a <varname>stdenv.mkDerivation</varname> call, + producing a new derivation based on the original one. This function is + available on all derivations produced by the + <varname>stdenv.mkDerivation</varname> function, which is most packages in + the nixpkgs expression <varname>pkgs</varname>. + </para> + + <para> + Example usage: +<programlisting> +helloWithDebug = pkgs.hello.overrideAttrs (oldAttrs: rec { + separateDebugInfo = true; +}); +</programlisting> + </para> + + <para> + In the above example, the <varname>separateDebugInfo</varname> attribute is + overridden to be true, thus building debug info for + <varname>helloWithDebug</varname>, while all other attributes will be + retained from the original <varname>hello</varname> package. + </para> + + <para> + The argument <varname>oldAttrs</varname> is conventionally used to refer to + the attr set originally passed to <varname>stdenv.mkDerivation</varname>. + </para> + + <note> + <para> + Note that <varname>separateDebugInfo</varname> is processed only by the + <varname>stdenv.mkDerivation</varname> function, not the generated, raw Nix + derivation. Thus, using <varname>overrideDerivation</varname> will not work + in this case, as it overrides only the attributes of the final derivation. + It is for this reason that <varname>overrideAttrs</varname> should be + preferred in (almost) all cases to <varname>overrideDerivation</varname>, + i.e. to allow using <varname>stdenv.mkDerivation</varname> to process input + arguments, as well as the fact that it is easier to use (you can use the + same attribute names you see in your Nix code, instead of the ones + generated (e.g. <varname>buildInputs</varname> vs + <varname>nativeBuildInputs</varname>), and it involves less typing). + </para> + </note> + </section> + + <section xml:id="sec-pkg-overrideDerivation"> + <title><pkg>.overrideDerivation</title> + + <warning> + <para> + You should prefer <varname>overrideAttrs</varname> in almost all cases, see + its documentation for the reasons why. + <varname>overrideDerivation</varname> is not deprecated and will continue + to work, but is less nice to use and does not have as many abilities as + <varname>overrideAttrs</varname>. + </para> + </warning> + + <warning> + <para> + Do not use this function in Nixpkgs as it evaluates a Derivation before + modifying it, which breaks package abstraction and removes error-checking + of function arguments. In addition, this evaluation-per-function + application incurs a performance penalty, which can become a problem if + many overrides are used. It is only intended for ad-hoc customisation, such + as in <filename>~/.config/nixpkgs/config.nix</filename>. + </para> + </warning> + + <para> + The function <varname>overrideDerivation</varname> creates a new derivation + based on an existing one by overriding the original's attributes with the + attribute set produced by the specified function. This function is available + on all derivations defined using the <varname>makeOverridable</varname> + function. Most standard derivation-producing functions, such as + <varname>stdenv.mkDerivation</varname>, are defined using this function, + which means most packages in the nixpkgs expression, + <varname>pkgs</varname>, have this function. + </para> + + <para> + Example usage: +<programlisting> +mySed = pkgs.gnused.overrideDerivation (oldAttrs: { + name = "sed-4.2.2-pre"; + src = fetchurl { + url = ftp://alpha.gnu.org/gnu/sed/sed-4.2.2-pre.tar.bz2; + sha256 = "11nq06d131y4wmf3drm0yk502d2xc6n5qy82cg88rb9nqd2lj41k"; + }; + patches = []; +}); +</programlisting> + </para> + + <para> + In the above example, the <varname>name</varname>, <varname>src</varname>, + and <varname>patches</varname> of the derivation will be overridden, while + all other attributes will be retained from the original derivation. + </para> + + <para> + The argument <varname>oldAttrs</varname> is used to refer to the attribute + set of the original derivation. + </para> + + <note> + <para> + A package's attributes are evaluated *before* being modified by the + <varname>overrideDerivation</varname> function. For example, the + <varname>name</varname> attribute reference in <varname>url = + "mirror://gnu/hello/${name}.tar.gz";</varname> is filled-in *before* the + <varname>overrideDerivation</varname> function modifies the attribute set. + This means that overriding the <varname>name</varname> attribute, in this + example, *will not* change the value of the <varname>url</varname> + attribute. Instead, we need to override both the <varname>name</varname> + *and* <varname>url</varname> attributes. + </para> + </note> + </section> + + <section xml:id="sec-lib-makeOverridable"> + <title>lib.makeOverridable</title> + + <para> + The function <varname>lib.makeOverridable</varname> is used to make the + result of a function easily customizable. This utility only makes sense for + functions that accept an argument set and return an attribute set. + </para> + + <para> + Example usage: +<programlisting> +f = { a, b }: { result = a+b; }; +c = lib.makeOverridable f { a = 1; b = 2; }; +</programlisting> + </para> + + <para> + The variable <varname>c</varname> is the value of the <varname>f</varname> + function applied with some default arguments. Hence the value of + <varname>c.result</varname> is <literal>3</literal>, in this example. + </para> + + <para> + The variable <varname>c</varname> however also has some additional + functions, like <link linkend="sec-pkg-override">c.override</link> which can + be used to override the default arguments. In this example the value of + <varname>(c.override { a = 4; }).result</varname> is 6. + </para> + </section> +</section> diff --git a/nixpkgs/doc/functions/shell.xml b/nixpkgs/doc/functions/shell.xml new file mode 100644 index 000000000000..e5031c9463c0 --- /dev/null +++ b/nixpkgs/doc/functions/shell.xml @@ -0,0 +1,26 @@ +<section xmlns="http://docbook.org/ns/docbook" + xmlns:xlink="http://www.w3.org/1999/xlink" + xmlns:xi="http://www.w3.org/2001/XInclude" + xml:id="sec-pkgs-mkShell"> + <title>pkgs.mkShell</title> + + <para> + <function>pkgs.mkShell</function> is a special kind of derivation that is + only useful when using it combined with <command>nix-shell</command>. It will + in fact fail to instantiate when invoked with <command>nix-build</command>. + </para> + + <section xml:id="sec-pkgs-mkShell-usage"> + <title>Usage</title> + +<programlisting><![CDATA[ +{ pkgs ? import <nixpkgs> {} }: +pkgs.mkShell { + # this will make all the build inputs from hello and gnutar + # available to the shell environment + inputsFrom = with pkgs; [ hello gnutar ]; + buildInputs = [ pkgs.gnumake ]; +} +]]></programlisting> + </section> +</section> |