WIP document derivations and deriving paths

And get rid of "store derivation" nonsense.

doc/manual/source/SUMMARY.md.in

@@ -22,6 +22,7 @@
   - [Store Object](store/store-object.md)
     - [Content-Addressing Store Objects](store/store-object/content-address.md)
   - [Store Path](store/store-path.md)
+  - [Derivation and Deriving Path](store/drv.md)
   - [Store Types](store/types/index.md)
 {{#include ./store/types/SUMMARY.md}}
 - [Nix Language](language/index.md)

doc/manual/source/command-ref/nix-build.md

@@ -37,11 +37,11 @@ directory containing at least a file named `default.nix`.
 
 `nix-build` is essentially a wrapper around
 [`nix-instantiate`](nix-instantiate.md) (to translate a high-level Nix
-expression to a low-level [store derivation]) and [`nix-store
+expression to a low-level [derivation]) and [`nix-store
 --realise`](@docroot@/command-ref/nix-store/realise.md) (to build the store
 derivation).
 
-[store derivation]: @docroot@/glossary.md#gloss-store-derivation
+[derivation]: @docroot@/glossary.md#gloss-derivation
 
 > **Warning**
 >
@@ -80,7 +80,7 @@ except for `--arg` and `--attr` / `-A` which are passed to [`nix-instantiate`](n
 
 ```console
 $ nix-build '<nixpkgs>' --attr firefox
-store derivation is /nix/store/qybprl8sz2lc...-firefox-1.5.0.7.drv
+derivation is /nix/store/qybprl8sz2lc...-firefox-1.5.0.7.drv
 /nix/store/d18hyl92g30l...-firefox-1.5.0.7
 
 $ ls -l result

doc/manual/source/command-ref/nix-copy-closure.md

@@ -42,9 +42,9 @@ When using public key authentication, you can avoid typing the passphrase with `
 
 - `--include-outputs`
 
-  Also copy the outputs of [store derivation]s included in the closure.
+  Also copy the outputs of [derivation]s included in the closure.
 
-  [store derivation]: @docroot@/glossary.md#gloss-store-derivation
+  [derivation]: @docroot@/glossary.md#gloss-store-derivation
 
 - `--use-substitutes` / `-s`
 

doc/manual/source/command-ref/nix-env/install.md

@@ -25,7 +25,7 @@ The arguments *args* map to store paths in a number of possible ways:
   These are [realised], and the resulting output paths are installed.
   Currently installed derivations with a name equal to the name of a derivation being added are removed unless the option `--preserve-installed` is specified.
 
-  [derivation]: @docroot@/glossary.md#gloss-derivation
+  [derivation expression]: @docroot@/glossary.md#gloss-derivation-expression
   [default Nix expression]: @docroot@/command-ref/files/default-nix-expression.md
   [realised]: @docroot@/glossary.md#gloss-realise
 
@@ -61,9 +61,9 @@ The arguments *args* map to store paths in a number of possible ways:
   The derivations returned by those function calls are installed.
   This allows derivations to be specified in an unambiguous way, which is necessary if there are multiple derivations with the same name.
 
-- If *args* are [store derivations](@docroot@/glossary.md#gloss-store-derivation), then these are [realised], and the resulting output paths are installed.
+- If *args* are [store paths] to [derivations](@docroot@/glossary.md#gloss-derivation), then those derivations are [realised], and the resulting output paths are installed.
 
-- If *args* are [store paths] that are not store derivations, then these are [realised] and installed.
+- If *args* are [store paths] not to derivations, then these are [realised] and installed.
 
 - By default all [outputs](@docroot@/language/derivations.md#attr-outputs) are installed for each [derivation].
   This can be overridden by adding a `meta.outputsToInstall` attribute on the derivation listing a subset of the output names.
@@ -193,7 +193,7 @@ To copy the store path with symbolic name `gcc` from another profile:
 $ nix-env --install --from-profile /nix/var/nix/profiles/foo gcc
 ```
 
-To install a specific [store derivation] (typically created by
+To install a specific [derivation] (typically created by
 `nix-instantiate`):
 
 ```console

doc/manual/source/command-ref/nix-env/query.md

@@ -125,7 +125,10 @@ derivation is shown unless `--no-name` is specified.
 
   - `--drv-path`
 
-    Print the path of the [store derivation](@docroot@/glossary.md#gloss-store-derivation).
+    Print the [store path] to the [derivation].
+
+    [store path]: @docroot@/glossary.md#gloss-store-path
+    [derivation]: @docroot@/glossary.md#gloss-derivation
 
   - `--out-path`
 

doc/manual/source/command-ref/nix-instantiate.md

@@ -1,6 +1,6 @@
 # Name
 
-`nix-instantiate` - instantiate store derivations from Nix expressions
+`nix-instantiate` - instantiate derivations from Nix expressions
 
 # Synopsis
 
@@ -17,13 +17,13 @@
 
 # Description
 
-The command `nix-instantiate` produces [store derivation]s from (high-level) Nix expressions.
+The command `nix-instantiate` produces [derivation]s from (high-level) Nix expressions.
 It evaluates the Nix expressions in each of *files* (which defaults to
 *./default.nix*). Each top-level expression should evaluate to a
 derivation, a list of derivations, or a set of derivations. The paths
-of the resulting store derivations are printed on standard output.
+of the resulting derivations are printed on standard output.
 
-[store derivation]: @docroot@/glossary.md#gloss-store-derivation
+[derivation]: @docroot@/glossary.md#gloss-derivation
 
 If *files* is the character `-`, then a Nix expression will be read from
 standard input.
@@ -42,8 +42,8 @@ standard input.
 - `--eval`
 
   Just parse and evaluate the input files, and print the resulting
-  values on standard output. No instantiation of store derivations
+  values on standard output.
-  takes place.
+  Derivations are not serialized and written to the store, but instead just discarded.
 
   > **Warning**
   >
@@ -128,7 +128,7 @@ standard input.
 
 # Examples
 
-Instantiate [store derivation]s from a Nix expression, and build them using `nix-store`:
+Instantiate [derivation]s from a Nix expression, and build them using `nix-store`:
 
 ```console
 $ nix-instantiate test.nix (instantiate)

doc/manual/source/command-ref/nix-store/query.md

@@ -26,14 +26,14 @@ symlink.
 
 - `--use-output` / `-u`
 
-  For each argument to the query that is a [store derivation], apply the
+  For each argument to the query that is a [derivation], apply the
   query to the output path of the derivation instead.
 
 - `--force-realise` / `-f`
 
   Realise each argument to the query first (see [`nix-store --realise`](./realise.md)).
 
-[store derivation]: @docroot@/glossary.md#gloss-store-derivation
+[derivation]: @docroot@/glossary.md#gloss-derivation
 
 # Queries
 
@@ -54,12 +54,12 @@ symlink.
   This query has one option:
 
     - `--include-outputs`
-      Also include the existing output paths of [store derivation]s,
+      Also include the existing output paths of [derivation]s,
       and their closures.
 
   This query can be used to implement various kinds of deployment. A
   *source deployment* is obtained by distributing the closure of a
-  store derivation. A *binary deployment* is obtained by distributing
+  derivation. A *binary deployment* is obtained by distributing
   the closure of an output path. A *cache deployment* (combined
   source/binary deployment, including binaries of build-time-only
   dependencies) is obtained by distributing the closure of a store
@@ -112,7 +112,7 @@ symlink.
   of the `dot` tool of AT\&T's [Graphviz
   package](http://www.graphviz.org/). This can be used to visualise
   dependency graphs. To obtain a build-time dependency graph, apply
-  this to a store derivation. To obtain a runtime dependency graph,
+  this to a derivation. To obtain a runtime dependency graph,
   apply it to an output path.
 
 - `--tree`
@@ -128,13 +128,13 @@ symlink.
   Prints the references graph of the store paths *paths* in the
   [GraphML](http://graphml.graphdrawing.org/) file format. This can be
   used to visualise dependency graphs. To obtain a build-time
-  dependency graph, apply this to a [store derivation]. To obtain a
+  dependency graph, apply this to a [derivation]. To obtain a
   runtime dependency graph, apply it to an output path.
 
 - `--binding` *name* / `-b` *name*
 
   Prints the value of the attribute *name* (i.e., environment
-  variable) of the [store derivation]s *paths*. It is an error for a
+  variable) of the [derivation]s *paths*. It is an error for a
   derivation to not have the specified attribute.
 
 - `--hash`

doc/manual/source/command-ref/nix-store/realise.md

@@ -11,10 +11,10 @@
 
 Each of *paths* is processed as follows:
 
-- If the path leads to a [store derivation]:
+- If the path leads to a [derivation]:
-  1. If it is not [valid], substitute the store derivation file itself.
+  1. If it is not [valid], substitute the derivation file itself.
   2. Realise its [output paths]:
-    - Try to fetch from [substituters] the [store objects] associated with the output paths in the store derivation's [closure].
+    - Try to fetch from [substituters] the [store objects] associated with the output paths in the derivation's [closure].
       - With [content-addressed derivations] (experimental):
         Determine the output paths to realise by querying content-addressed realisation entries in the [Nix database].
     - For any store paths that cannot be substituted, produce the required store objects:
@@ -23,11 +23,11 @@ Each of *paths* is processed as follows:
          <!-- TODO: Link to build process page #8888 -->
 - Otherwise, and if the path is not already valid: Try to fetch the associated [store objects] in the path's [closure] from [substituters].
 
-If no substitutes are available and no store derivation is given, realisation fails.
+If no substitutes are available and no derivation is given, realisation fails.
 
 [store paths]: @docroot@/store/store-path.md
 [valid]: @docroot@/glossary.md#gloss-validity
-[store derivation]: @docroot@/glossary.md#gloss-store-derivation
+[derivation]: @docroot@/glossary.md#gloss-derivation
 [output paths]: @docroot@/glossary.md#gloss-output-path
 [store objects]: @docroot@/store/store-object.md
 [closure]: @docroot@/glossary.md#gloss-closure
@@ -71,7 +71,7 @@ For non-derivation arguments, the argument itself is printed.
 
 # Examples
 
-This operation is typically used to build [store derivation]s produced by
+This operation is typically used to build [derivation]s produced by
 [`nix-instantiate`](@docroot@/command-ref/nix-instantiate.md):
 
 ```console

doc/manual/source/glossary.md

@@ -21,31 +21,26 @@
 
 - [derivation]{#gloss-derivation}
 
-  A description of a build task. The result of a derivation is a
+  A single build task.
-  store object. Derivations declared in Nix expressions are specified
+  See [Derivation](@docroot@/doc/manual/src/store/drv.md#Derivation) for details.
-  using the [`derivation` primitive](./language/derivations.md). These are
-  translated into low-level *store derivations* (implicitly by
-  `nix-build`, or explicitly by `nix-instantiate`).
 
   [derivation]: #gloss-derivation
 
-- [store derivation]{#gloss-store-derivation}
+- [derivation expression]{#gloss-derivation}
 
-  A [derivation] represented as a `.drv` file in the [store].
+  A description of a [derivation] in the Nix language.
-  It has a [store path], like any [store object].
+  The result of a derivation is a store object.
-  It is the [instantiated][instantiate] form of a derivation.
+  Derivations are typically specified in Nix expressions using the [`derivation` primitive](./language/derivations.md).
+  These are translated into low-level *derivations* (implicitly by
+  `nix-env` and `nix-build`, or explicitly by `nix-instantiate`).
 
-  Example: `/nix/store/g946hcz4c8mdvq2g8vxx42z51qb71rvp-git-2.38.1.drv`
+  [derivation expression]: #gloss-derivation-expression
-
-  See [`nix derivation show`](./command-ref/new-cli/nix3-derivation-show.md) (experimental) for displaying the contents of store derivations.
-
-  [store derivation]: #gloss-store-derivation
 
 - [instantiate]{#gloss-instantiate}, instantiation
 
-  Save an evaluated [derivation] as a [store derivation] in the Nix [store].
+  Translate a [derivation expression] into a [derivation].
 
-  See [`nix-instantiate`](./command-ref/nix-instantiate.md), which produces a store derivation from a Nix expression that evaluates to a derivation.
+  See [`nix-instantiate`](./command-ref/nix-instantiate.md), which produces a derivation from a Nix expression that evaluates to a derivation.
 
   [instantiate]: #gloss-instantiate
 
@@ -188,7 +183,7 @@
   >
   > The contents of a `.nix` file form a Nix expression.
 
-  Nix expressions specify [derivations][derivation], which are [instantiated][instantiate] into the Nix store as [store derivations][store derivation].
+  Nix expressions specify [derivation expressions][derivation expression], which are [instantiated][instantiate] into the Nix store as [derivations][derivation].
   These derivations can then be [realised][realise] to produce [outputs][output].
 
   > **Example**
@@ -257,7 +252,7 @@
 
 - [deriver]{#gloss-deriver}
 
-  The [store derivation] that produced an [output path].
+  The [derivation] that produced an [output path].
 
   The deriver for an output path can be queried with the `--deriver` option to
   [`nix-store --query`](@docroot@/command-ref/nix-store/query.md).

doc/manual/source/language/derivations.md

@@ -4,9 +4,9 @@ The most important built-in function is `derivation`, which is used to describe
 a specification for running an executable on precisely defined input files to repeatably produce output files at uniquely determined file system paths.
 
 It takes as input an attribute set, the attributes of which specify the inputs to the process.
-It outputs an attribute set, and produces a [store derivation] as a side effect of evaluation.
+It outputs an attribute set, and produces a [derivation] as a side effect of evaluation.
 
-[store derivation]: @docroot@/glossary.md#gloss-store-derivation
+[derivation]: @docroot@/glossary.md#gloss-derivation
 
 ## Input attributes
 
@@ -15,7 +15,7 @@ It outputs an attribute set, and produces a [store derivation] as a side effect
 - [`name`]{#attr-name} ([String](@docroot@/language/types.md#type-string))
 
   A symbolic name for the derivation.
-  It is added to the [store path] of the corresponding [store derivation] as well as to its [output paths](@docroot@/glossary.md#gloss-output-path).
+  It is added to the [store path] of the corresponding [derivation] as well as to its [output paths](@docroot@/glossary.md#gloss-output-path).
 
   [store path]: @docroot@/store/store-path.md
 
@@ -28,7 +28,7 @@ It outputs an attribute set, and produces a [store derivation] as a side effect
   > }
   > ```
   >
-  > The store derivation's path will be `/nix/store/<hash>-hello.drv`.
+  > The derivation's path will be `/nix/store/<hash>-hello.drv`.
   > The [output](#attr-outputs) paths will be of the form `/nix/store/<hash>-hello[-<output>]`
 
 - [`system`]{#attr-system} ([String](@docroot@/language/types.md#type-string))
@@ -182,7 +182,7 @@ It outputs an attribute set, and produces a [store derivation] as a side effect
   > }
   > ```
   >
-  > The store derivation path will be `/nix/store/<hash>-example.drv`.
+  > The derivation path will be `/nix/store/<hash>-example.drv`.
   > The output paths will be
   > - `/nix/store/<hash>-example-lib`
   > - `/nix/store/<hash>-example-dev`

doc/manual/source/language/import-from-derivation.md

@@ -71,9 +71,10 @@ Boxes are data structures, arrow labels are transformations.
 |       evaluate       |             |                        |
 |          |           |             |                        |
 |          V           |             |                        |
-|    .------------.    |             |  .------------------.  |
+|    .------------.    |             |                        |
-|    | derivation |----|-instantiate-|->| store derivation |  |
+|    | derivation |    |             |     .------------.     |
-|    '------------'    |             |  '------------------'  |
+|    | expression |----|-instantiate-|---->| derivation |     |
+|    '------------'    |             |     '------------'     |
 |                      |             |           |            |
 |                      |             |        realise         |
 |                      |             |           |            |

doc/manual/source/language/string-interpolation.md

@@ -22,7 +22,7 @@ Rather than writing
 "--with-freetype2-library=" + freetype + "/lib"
 ```
 
-(where `freetype` is a [derivation]), you can instead write
+(where `freetype` is an [output path]), you can instead write
 
 [derivation]: @docroot@/glossary.md#gloss-derivation
 
@@ -148,7 +148,7 @@ An expression that is interpolated must evaluate to one of the following:
   - `__toString` must be a function that takes the attribute set itself and returns a string
   - `outPath` must be a string
 
-  This includes [derivations](./derivations.md) or [flake inputs](@docroot@/command-ref/new-cli/nix3-flake.md#flake-inputs) (experimental).
+  This includes [derivation expressions](./derivations.md) or [flake inputs](@docroot@/command-ref/new-cli/nix3-flake.md#flake-inputs) (experimental).
 
 A string interpolates to itself.
 

doc/manual/source/protocols/derivation-aterm.md

@@ -1,6 +1,6 @@
 # Derivation "ATerm" file format
 
-For historical reasons, [derivations](@docroot@/glossary.md#gloss-store-derivation) are stored on-disk in [ATerm](https://homepages.cwi.nl/~daybuild/daily-books/technology/aterm-guide/aterm-guide.html) format.
+For historical reasons, [derivations](@docroot@/glossary.md#gloss-derivation) are stored on-disk in [ATerm](https://homepages.cwi.nl/~daybuild/daily-books/technology/aterm-guide/aterm-guide.html) format.
 
 Derivations are serialised in one of the following formats:
 

doc/manual/source/release-notes/rl-0.8.md

@@ -97,7 +97,7 @@ Nix 0.8 has the following improvements:
 
             $ nix-env -i --from-profile .../other-profile firefox
 
-      - Install a store derivation directly (bypassing the Nix
+      - Install a derivation directly (bypassing the Nix
         expression language entirely):
 
             $ nix-env -i /nix/store/z58v41v21xd3...-aterm-2.3.1.drv

doc/manual/source/release-notes/rl-2.0.md

@@ -198,7 +198,7 @@ This release has the following new features:
         NAR format. This replaces `nix-store --dump`.
 
       - `nix
-                                                                        show-derivation` displays a store derivation in JSON format.
+                                                                        show-derivation` displays a derivation in JSON format.
         This is an alternative to `pp-aterm`.
 
       - `nix

doc/manual/source/release-notes/rl-2.13.md

@@ -22,7 +22,7 @@
   accurate error locations. A short excerpt of the trace is now shown by
   default when an error occurs.
 
-* Allow explicitly selecting outputs in a store derivation installable, just like we can do with other sorts of installables.
+* Allow explicitly selecting outputs in a derivation installable, just like we can do with other sorts of installables.
   For example,
   ```shell-session
   # nix build /nix/store/gzaflydcr6sb3567hap9q6srzx8ggdgg-glibc-2.33-78.drv^dev

doc/manual/source/release-notes/rl-2.15.md

@@ -11,7 +11,7 @@
   As the choice of hash formats is no longer binary, the `--base16` flag is also added
   to explicitly specify the Base16 format, which is still the default.
 
-* The special handling of an [installable](../command-ref/new-cli/nix.md#installables) with `.drv` suffix being interpreted as all of the given [store derivation](@docroot@/glossary.md#gloss-store-derivation)'s output paths is removed, and instead taken as the literal store path that it represents.
+* The special handling of an [installable](../command-ref/new-cli/nix.md#installables) with `.drv` suffix being interpreted as all of the given [derivation](@docroot@/glossary.md#gloss-derivation)'s output paths is removed, and instead taken as the literal store path that it represents.
 
   The new `^` syntax for store paths introduced in Nix 2.13 allows explicitly referencing output paths of a derivation.
   Using this is better and more clear than relying on the now-removed `.drv` special handling.

doc/manual/source/store/drv.md

@@ -0,0 +1,172 @@
+# Derivation and Deriving Path
+
+So far, we have covered "inert" store objects.
+But the point of the Nix store layer is to be a build system.
+Other system (like Git or IPFS) also store and transfer immutable data, but they don't concern themselves with *how* that data was created.
+
+This is where Nix distinguishes itself.
+*Derivations* represent individual build steps, and *deriving paths* are needed to to the *outputs* of those build steps.
+The two concepts need to be introduced together because, as described below, each depends on the other.
+
+## Derivation
+
+What is natural Unix analog for a build step *in action*?
+Answer: a process that will eventually exit, leaving behind some output date.
+What is the natural way to *plan* such a step?
+An `execve` system call.
+
+A derivation consists of:
+
+ - A (base) name
+
+ - A set of *outputs*, consisting of names and possibly other data
+
+ - A set of *inputs*, a set of deriving paths
+
+ - Everything needed for an `execve` system call:
+   1. Path to executable
+   2. A list of arguments (except for `argv[0]`, which is taken from the path in the usual way)
+   3. A set of environment variables.
+
+ - A two-component "system" name (e.g. `x86_64-linux`) where the executable is to run.
+
+The path and list/set elements of the other two will presumably consist wholly or partly of store paths.
+But just as we stored the references contained in the file data separately for store objects, so we store the set of inputs separately.
+
+The last bit of information is to take advantage of the fact that Nix allows *heterogenous* build plans, were not all steps can be run on the same machine or same sort of machine.
+
+The process's job is to produce the outputs, but have no other important side effects.
+The rules around this will be discussed in following sections.
+
+### Output name
+
+Most outputs are named `drv.name + '-' + outputName`.
+However, an output named "out" is just has name `drv.name`.
+This is to allow derivations with a single output to avoid a superfluous `-<outputName>` in their single output's name when no disambiguation is needed.
+
+### Placeholder
+
+TODO
+
+### Referencing
+
+Derivations are always referred to by the store path of the store object they are encoded to.
+The store path name is the derivation name with `.drv` suffixed at the end.
+The store path digest we will explain in a following section after we go over the different variants of derivations, as the exact algorithm depends on them.
+Suffice to say for now, it is (a form of) content addressing based on the derivation and its inputs.
+
+## Deriving path
+
+Deriving references are close to their abstract version, but using `StorePath` as the type of all references, matching the end of the previous subsection.
+
+In pseudo code:
+
+```idris
+type OutputName = String
+
+data DerivingPath
+  = ConstantPath { path : StorePath }
+  | Output {
+      drv    : StorePath,
+      output : OutputName,
+    }
+```
+
+## Encoding
+
+### Derivation
+
+- The name is not encoded, because we can just get it from the store object!
+
+:::{.note}
+Brief amusing history of PP-ATerm
+:::
+
+#### `inputSrcs` vs `inputDrvs`
+
+### Deriving Path
+
+Constant deriving paths are encoded simply as the underlying store path is.
+Thus, we see that every encoded store path is also a valid encoded (constant) deriving path.
+
+Output deriving paths are encoded by
+
+- encoding of a store path referring to a derivation
+
+- a separator (`^` or `!` depending on context)
+
+- the name of an output
+
+An example would be:
+
+```
+/nix/store/lxrn8v5aamkikg6agxwdqd1jz7746wz4-firefox-98.0.2.drv^out
+```
+
+This parses like so:
+
+```
+/nix/store/lxrn8v5aamkikg6agxwdqd1jz7746wz4-firefox-98.0.2.drv^out
+|------------------------------------------------------------| |-|
+store path (usual encoding)                                    output name
+                                                          |--|
+                                                          note the ".drv"
+```
+
+## Extending the model to be higher-order
+
+**Experimental feature**: [`dynamic-derivations`](@docroot@/contributing/experimental-features.md#xp-feature-dynamic-derivations)
+
+We can apply the same extension discussed for the abstract model to the concrete model.
+Again, only the data type for Deriving Paths needs to be modified.
+Derivations are the same except for using the new extended deriving path data type.
+
+```idris
+type OutputName = String
+
+data DerivingPath
+  = ConstantPath { storeObj : StorePath }
+  | Output {
+      drv    : DerivingPath, -- changed
+      output : OutputName,
+    }
+```
+
+Now, the `drv` field of `BuiltObject` is itself a `DerivingPath` instead of an `StorePath`.
+
+Under this extended model, `DerivingPath`s are thus inductively built up from an `ConstantPath`, contains in 0 or more outer `Outputs`.
+
+### Encoding
+
+The encoding is adjusted in a very simplest way, merely displaying the same
+
+```
+/nix/store/lxrn8v5aamkikg6agxwdqd1jz7746wz4-firefox-98.0.2.drv^foo.drv^bar.drv^out
+|----------------------------------------------------------------------------| |-|
+inner deriving path (usual encoding)                                           output name
+|--------------------------------------------------------------------| |-----|
+even more inner deriving path (usual encoding)                         output name
+|------------------------------------------------------------| |-----|
+innermost constant store path (usual encoding)                 output name
+```
+
+## Extra extensions
+
+### `__structuredAttrs`
+
+Historically speaking, most users of Nix made GNU Bash with a script the command run, regardless of what they were doing.
+Bash variable are automatically created from env vars, but bash also supports array and string-keyed map variables in addition to string variables.
+People also usually create derivations using language which also support these richer data types.
+It was thus desired a way to get this data from the language "planning" the derivation to language to bash, the language evaluated at "run time".
+
+`__structuredAttrs` does this by smuggling inside the core derivation format a map of named richer data.
+At run time, this becomes two things:
+
+1. A JSON file containing that map.
+2. A bash script setting those variables.
+
+The bash command can be passed a script which will "source" that Nix-created bash script, setting those variables with the richer data.
+The outer script can then do whatever it likes with those richer variables as input.
+
+However, since derivations can already contain arbitary input sources, the vast majority of `__structuredAttrs` can be handled by upper layers.
+We might consider implementing `__structuredAttrs` in higher layers in the future, and simplifying the store layer.

src/libcmd/command.cc

@@ -144,7 +144,7 @@ MixOperateOnOptions::MixOperateOnOptions()
     addFlag({
         .longName = "derivation",
         .description =
-            "Operate on the [store derivation](@docroot@/glossary.md#gloss-store-derivation) rather than its outputs.",
+            "Operate on the [derivation](@docroot@/glossary.md#gloss-derivation) rather than its outputs.",
         .category = installablesCategory,
         .handler = {&operateOn, OperateOn::Derivation},
     });

src/libcmd/installables.hh

@@ -24,7 +24,7 @@ enum class Realise {
     /**
      * Don't build the derivation.
      *
-     * Postcondition: the store derivation exists.
+     * Postcondition: the derivation exists.
      */
     Derivation,
     /**

src/libexpr/eval-cache.cc

@@ -777,7 +777,7 @@ StorePath AttrCursor::forceDerivation()
            been garbage-collected. So force it to be regenerated. */
         aDrvPath->forceValue();
         if (!root->state.store->isValidPath(drvPath))
-            throw Error("don't know how to recreate store derivation '%s'!",
+            throw Error("don't know how to recreate derivation '%s'!",
                 root->state.store->printStorePath(drvPath));
     }
     return drvPath;

src/libexpr/primops.cc

@@ -1505,7 +1505,7 @@ static void derivationStrictInternal(
     }
 
     else {
-        /* Compute a hash over the "masked" store derivation, which is
+        /* Compute a hash over the "masked" derivation, which is
            the final one except that in the list of outputs, the
            output paths are empty strings, and the corresponding
            environment variables have an empty value.  This ensures
@@ -1551,7 +1551,7 @@ static void derivationStrictInternal(
     printMsg(lvlChatty, "instantiated '%1%' -> '%2%'", drvName, drvPathS);
 
     /* Optimisation, but required in read-only mode! because in that
-       case we don't actually write store derivations, so we can't
+       case we don't actually write derivations, so we can't
        read them later. */
     {
         auto h = hashDerivationModulo(*state.store, drv, false);

src/libexpr/primops/context.cc

@@ -236,7 +236,7 @@ static RegisterPrimOp primop_getContext({
       Return the string context of *s*.
 
       The string context tracks references to derivations within a string.
-      It is represented as an attribute set of [store derivation](@docroot@/glossary.md#gloss-store-derivation) paths mapping to output names.
+      It is represented as an attribute set of [derivation](@docroot@/glossary.md#gloss-derivation) paths mapping to output names.
 
       Using [string interpolation](@docroot@/language/string-interpolation.md) on a derivation will add that derivation to the string context.
       For example,

src/nix/derivation-add.cc

@@ -14,7 +14,7 @@ struct CmdAddDerivation : MixDryRun, StoreCommand
 {
     std::string description() override
     {
-        return "Add a store derivation";
+        return "Add a derivation";
     }
 
     std::string doc() override

src/nix/derivation-add.md

@@ -3,17 +3,16 @@ R""(
 # Description
 
 This command reads from standard input a JSON representation of a
-[store derivation].
+[derivation].
 
 Store derivations are used internally by Nix. They are store paths with
 extension `.drv` that represent the build-time dependency graph to which
 a Nix expression evaluates.
 
-
+[derivation]: @docroot@/glossary.md#gloss-derivation
-[store derivation]: @docroot@/glossary.md#gloss-store-derivation
 
 `nix derivation add` takes a single derivation in the following format:
 
-{{#include ../../protocols/json/derivation.md}}
+{{#include @docroot@/protocols/json/derivation.md}}
 
 )""

src/nix/derivation-show.cc

@@ -1,5 +1,4 @@
-// FIXME: integrate this with nix path-info?
+// FIXME: integrate this with `nix path-info`?
-// FIXME: rename to 'nix store derivation show' or 'nix debug derivation show'?
 
 #include "command.hh"
 #include "common-args.hh"
@@ -27,7 +26,7 @@ struct CmdShowDerivation : InstallablesCommand
 
     std::string description() override
     {
-        return "show the contents of a store derivation";
+        return "show the contents of a derivation";
     }
 
     std::string doc() override

src/nix/derivation-show.md

@@ -2,7 +2,7 @@ R""(
 
 # Examples
 
-* Show the [store derivation] that results from evaluating the Hello
+* Show the [derivation] that results from evaluating the Hello
   package:
 
   ```console
@@ -37,7 +37,7 @@ R""(
 # Description
 
 This command prints on standard output a JSON representation of the
-[store derivation]s to which [*installables*](./nix.md#installables) evaluate.
+[derivation]s to which [*installables*](./nix.md#installables) evaluate.
 
 Store derivations are used internally by Nix. They are store paths with
 extension `.drv` that represent the build-time dependency graph to which
@@ -46,7 +46,7 @@ a Nix expression evaluates.
 By default, this command only shows top-level derivations, but with
 `--recursive`, it also shows their dependencies.
 
-[store derivation]: @docroot@/glossary.md#gloss-store-derivation
+[derivation]: ../../glossary.md#gloss-derivation
 
 `nix derivation show` outputs a JSON map of [store path]s to derivations in the following format:
 

src/nix/nix.md

@@ -144,11 +144,11 @@ Example: `/nix/store/v5sv61sszx301i0x6xysaqzla09nksnd-hello-2.10`
 
 These are paths inside the Nix store, or symlinks that resolve to a path in the Nix store.
 
-A [store derivation] is also addressed by store path.
+A [derivation] is also addressed by store path.
 
 Example: `/nix/store/p7gp6lxdg32h4ka1q398wd9r2zkbbz2v-hello-2.10.drv`
 
-If you want to refer to an output path of that store derivation, add the output name preceded by a caret (`^`).
+If you want to refer to an output path of that derivation, add the output name preceded by a caret (`^`).
 
 Example: `/nix/store/p7gp6lxdg32h4ka1q398wd9r2zkbbz2v-hello-2.10.drv^out`
 
@@ -244,10 +244,10 @@ operate are determined as follows:
   a command like `nix shell nixpkgs#libxml2` will provide only those
   two outputs by default.
 
-  Note that a [store derivation] (given by its `.drv` file store path) doesn't have
+  Note that a [derivation] (given by its `.drv` file store path) doesn't have
   any attributes like `meta`, and thus this case doesn't apply to it.
 
-  [store derivation]: @docroot@/glossary.md#gloss-store-derivation
+  [derivation]: @docroot@/glossary.md#gloss-derivation
 
 * Otherwise, Nix will use all outputs of the derivation.
 

src/nix/path-info.md

@@ -68,9 +68,9 @@ R""(
   ]
   ```
 
-* Print the path of the [store derivation] produced by `nixpkgs#hello`:
+* Print the path of the [derivation] produced by `nixpkgs#hello`:
 
-  [store derivation]: @docroot@/glossary.md#gloss-store-derivation
+  [derivation]: @docroot@/glossary.md#gloss-derivation
 
   ```console
   # nix path-info --derivation nixpkgs#hello

src/nix/search.md

@@ -62,8 +62,8 @@ R""(
 
 # Description
 
-`nix search` searches [*installable*](./nix.md#installables) (which can be evaluated, that is, a
+`nix search` searches [*installable*](./nix.md#installables) that can be evaluated, that is, a
-flake or Nix expression, but not a store path or store derivation path) for packages whose name or description matches all of the
+flake or Nix expression, but not a [store path] or [deriving path]) for packages whose name or description matches all of the
 regular expressions *regex*. For each matching package, It prints the
 full attribute name (from the root of the [installable](./nix.md#installables)), the version
 and the `meta.description` field, highlighting the substrings that
@@ -75,6 +75,9 @@ it avoids highlighting the entire name and description of every package.
 > Note that in this context, `^` is the regex character to match the beginning of a string, *not* the delimiter for
 > [selecting a derivation output](@docroot@/command-ref/new-cli/nix.md#derivation-output-selection).
 
+[store path]: @docroot@/glossary.md#gloss-store-path
+[deriving path]: @docroot@/glossary.md#gloss-deriving-path
+
 # Flake output attributes
 
 If no flake output attribute is given, `nix search` searches for

src/nix/store-copy-log.md

@@ -18,9 +18,9 @@ R""(
   (The flag `--substituters ''` avoids querying
   `https://cache.nixos.org` for the log.)
 
-* To copy the log for a specific [store derivation] via SSH:
+* To copy the log for a specific [derivation] via SSH:
 
-  [store derivation]: @docroot@/glossary.md#gloss-store-derivation
+  [derivation]: @docroot@/glossary.md#gloss--derivation
 
   ```console
   # nix store copy-log --to ssh-ng://machine /nix/store/ilgm50plpmcgjhcp33z6n4qbnpqfhxym-glibc-2.33-59.drv