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-rw-r--r--doc/manual/src/architecture/store/store.md57
1 files changed, 32 insertions, 25 deletions
diff --git a/doc/manual/src/architecture/store/store.md b/doc/manual/src/architecture/store/store.md
index 1640944ad..5a0f4a2df 100644
--- a/doc/manual/src/architecture/store/store.md
+++ b/doc/manual/src/architecture/store/store.md
@@ -2,33 +2,49 @@
A Nix store is a collection of *store objects*.
-A store object can hold arbitrary *data* and *references* to other store objects.
-Nix makes no distinction if store objects are used as build inputs, build results, or build tasks.
+A store object can hold
-```haskell
-data Store = Set StoreObject
+- arbitrary *data*
+- *references* to other store objects.
-data StoreObject = StoreObject {
- data :: Data
-, references :: Set Reference
-}
-```
+Nix makes no distinction if store objects are build inputs, build results, or build tasks.
A Nix store can *add*, *retrieve*, and *delete* store objects.
+ [ data ]
+ |
+ V
+ [ store ] ---> add ----> [ store' ] [ reference ]
+
+<!-- -->
+
+ [ reference ]
+ |
+ V
+ [ store ] ---> get ----> [ store object ]
+
+<!-- -->
+
+ [ reference ]
+ |
+ V
+ [ store ] --> delete --> [ store' ]
+
+
It can *perform builds*, that is, create new store objects by transforming build inputs into build outputs, using instructions from the build tasks.
+
+ [ reference ]
+ |
+ V
+ [ store ] --> build --(maybe)--> [ store' ] [ reference' ]
+
+
As it keeps track of references, it can [garbage-collect][garbage-collection] unused store objects.
-```haskell
-add :: Store -> Data -> (Store, Reference)
-get :: Store -> Reference -> StoreObject
-delete :: Store -> Reference -> Store
-build :: Store -> Reference -> Maybe (Store, Reference)
+ [ store ] --> collect garbage --> [ store' ]
-collectGarbage :: Store -> Store
-```
Store objects are [immutable][immutable-object]: once created, they do not change until they are deleted.
@@ -41,15 +57,6 @@ An added store object cannot have references, unless it is a build task.
Building a store object will add appropriate references, according to provided build instructions.
These references can only come from declared build inputs, and are not known to build instructions a priori.
-```haskell
-data Data = Data | Task BuildTask
-
-data BuildTask = BuildTask {
- instructions :: Reference
-, inputs :: [Reference]
-}
-```
-
A store object cannot be deleted as long as it is reachable from a reference still in use.
Garbage collection will delete all store objects that cannot be reached from any reference in use.