Merge pull request #12999 from fricklerhandwerk/language

Nix language reference: highlight characteristic features

Author: Mic92

doc/manual/source/language/index.md

@@ -11,7 +11,14 @@ The language is:
 
 - *domain-specific*
 
-  It comes with [built-in functions](@docroot@/language/builtins.md) to integrate with the Nix store, which manages files and performs the derivations declared in the Nix language.
+  The Nix language is purpose-built for working with text files.
+  Its most characteristic features are:
+
+  - [File system path primitives](@docroot@/language/types.md#type-path), for accessing source files
+  - [Indented strings](@docroot@/language/string-literals.md) and [string interpolation](@docroot@/language/string-interpolation.md), for creating file contents
+  - [Strings with contexts](@docroot@/language/string-context.md), for transparently linking files
+
+  It comes with [built-in functions](@docroot@/language/builtins.md) to integrate with the [Nix store](@docroot@/store/index.md), which manages files and enables [realising](@docroot@/glossary.md#gloss-realise) derivations declared in the Nix language.
 
 - *declarative*
 

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

@@ -13,8 +13,8 @@ The purpose of string contexts is to collect non-string values attached to strin
 [string concatenation](./operators.md#string-concatenation),
 [string interpolation](./string-interpolation.md),
 and similar operations.
-The idea is that a user can combine together values to create a build instructions for derivations without manually keeping track of where they come from.
-Then the Nix language implicitly does that bookkeeping to efficiently obtain the closure of derivation inputs.
+The idea is that a user can reference other files when creating text files through Nix expressions, without manually keeping track of the exact paths.
+Nix will ensure that the all referenced files are accessible – that all [store paths](@docroot@/glossary.md#gloss-store-path) are [valid](@docroot@/glossary.md#gloss-validitiy).
 
 > **Note**
 >