path: root/doc/manual/glossary.xml

<appendix><title>Glossary</title>

<glosslist>


<glossentry><glossterm>derivation</glossterm>

  <glossdef><para>A description of a build action.  The result of a
  derivation is a store object.</para></glossdef>

</glossentry>


<glossentry><glossterm>store</glossterm>

  <glossdef><para>The location in the file system where store objects
  live.  Typically <filename>/nix/store</filename>.</para></glossdef>

</glossentry>


<glossentry><glossterm>store path</glossterm>

  <glossdef><para>The location in the file system of a store object,
  i.e., an immediate child of the Nix store
  directory.</para></glossdef>

</glossentry>


<glossentry><glossterm>store object</glossterm>

  <glossdef><para>A file that is an immediate child of the Nix store
  directory.  These can be regular files, but also entire directory
  trees.  Store objects can be sources (objects copied from outside of
  the store), derivation outputs (objects produced by running a build
  action), or derivations (files describing a build
  action).</para></glossdef>

</glossentry>


<glossentry><glossterm>substitute</glossterm>

  <glossdef><para>A substitute is a command invocation stored in the
  Nix database that describes how to build a store object, bypassing
  normal the build mechanism (i.e., derivations).  Typically, the
  substitute builds the store object by downloading a pre-built
  version of the store object from some server.</para></glossdef>

</glossentry>


<glossentry><glossterm>purity</glossterm>

  <glossdef><para>The assumption that equal Nix derivations when run
  always produce the same output.  This cannot be guaranteed in
  general (e.g., a builder can rely on external inputs such as the
  network or the system time) but the Nix model assumes
  it.</para></glossdef>

</glossentry>


<glossentry><glossterm>Nix expression</glossterm>

  <glossdef><para>A high-level description of software components and
  compositions thereof.  Deploying software using Nix entails writing
  Nix expressions for your components.  Nix expressions are translated
  to derivations that are stored in the Nix store.  These derivations
  can then be built.</para></glossdef>

</glossentry>


</glosslist>


</appendix>