From 86d3f0ab526899e27c6d7b9aa6fb71b17b75e6d5 Mon Sep 17 00:00:00 2001
From: Ruben Bartelink <ruben@bartelink.com>
Date: Thu, 16 Nov 2023 23:56:51 +0000
Subject: [PATCH] Remove Accumulator

---
 DOCUMENTATION.md             |  6 ++----
 samples/Store/Domain/Cart.fs | 42 ------------------------------------
 2 files changed, 2 insertions(+), 46 deletions(-)

diff --git a/DOCUMENTATION.md b/DOCUMENTATION.md
index cc3cd52f7..42f17f757 100755
--- a/DOCUMENTATION.md
+++ b/DOCUMENTATION.md
@@ -1363,7 +1363,7 @@ which can then summarize the overall transaction.
 ### Idiomatic approach - composed method based on side-effect free functions
 
 There's an example of such a case in the
-[Cart's Domain Service](https://github.com/jet/equinox/blob/master/samples/Store/Domain/Cart.fs#L128):
+[Cart's Domain Service](https://github.com/jet/equinox/blob/master/samples/Store/Domain/Cart.fs#L106):
 
 ```fsharp
 let interpretMany fold interpreters (state: 'state): 'state * 'event[] =
@@ -1392,9 +1392,7 @@ _NOTE: This is an example of an alternate approach provided as a counterpoint -
 there's no need to read it as the preceding approach is the recommended one is
 advised as a default strategy to use_
 
-As illustrated in [Cart's Domain
-Service](https://github.com/jet/equinox/blob/master/samples/Store/Domain/Cart.fs#L99),
-an alternate approach is to encapsulate the folding (Equinox in V1 exposed an
+An alternate approach is to encapsulate the folding (Equinox in V1 exposed an
 interface that encouraged such patterns; this was removed in two steps, as code
 written using the idiomatic approach is [intrinsically simpler, even if it
 seems not as Easy](https://www.infoq.com/presentations/Simple-Made-Easy/) at
diff --git a/samples/Store/Domain/Cart.fs b/samples/Store/Domain/Cart.fs
index bc5b4ee3e..b6dc8630b 100644
--- a/samples/Store/Domain/Cart.fs
+++ b/samples/Store/Domain/Cart.fs
@@ -103,40 +103,6 @@ let interpret command (state: Fold.State) =
         | SyncItem (Context c, skuId, None, w) ->
             yield! maybePropChanges c skuId w |]
 
-#if ACCUMULATOR
-// This was once part of the core Equinox functionality, but was removed in https://github.com/jet/equinox/pull/184
-// it remains here solely to serve as an example; the PR details the considerations leading to this conclusion
-
-/// Maintains a rolling folded State while Accumulating Events pended as part of a decision flow
-type Accumulator<'event, 'state>(fold: 'state -> 'event[] -> 'state, originState: 'state) =
-    let accumulated = ResizeArray<'event>()
-
-    /// The Events that have thus far been pended via the `decide` functions `Execute`/`Decide`d during the course of this flow
-    member _.Accumulated: 'event[] =
-        accumulated.ToArray()
-
-    /// The current folded State, based on the Stream's `originState` + any events that have been Accumulated during the the decision flow
-    member _.State: 'state =
-        accumulated |> fold originState
-
-    /// Invoke a decision function, gathering the events (if any) that it decides are necessary into the `Accumulated` sequence
-    member x.Transact(interpret: 'state -> 'event[]): unit =
-        interpret x.State |> accumulated.AddRange
-    /// Invoke an Async decision function, gathering the events (if any) that it decides are necessary into the `Accumulated` sequence
-    member x.Transact(interpret: 'state -> Async<'event[]>): Async<unit> = async {
-        let! events = interpret x.State
-        accumulated.AddRange events }
-    /// Invoke a decision function, while also propagating a result yielded as the fst of an (result, events) pair
-    member x.Transact(decide: 'state -> 'result * 'event[]): 'result =
-        let result, newEvents = decide x.State
-        accumulated.AddRange newEvents
-        result
-    /// Invoke a decision function, while also propagating a result yielded as the fst of an (result, events) pair
-    member x.Transact(decide: 'state -> Async<'result * 'event[]>): Async<'result> = async {
-        let! result, newEvents = decide x.State
-        accumulated.AddRange newEvents
-        return result }
-#else
 let interpretMany fold interpreters (state: 'state): 'state * 'event[] =
     let mutable state = state
     let events = [|
@@ -145,21 +111,13 @@ let interpretMany fold interpreters (state: 'state): 'state * 'event[] =
             yield! events
             state <- fold state events |]
     state, events
-#endif
 
 type Service internal (resolve: CartId -> Equinox.Decider<Events.Event, Fold.State>) =
 
     member _.Run(cartId, optimistic, commands: Command seq, ?prepare): Async<Fold.State> =
         let interpret state = async {
             match prepare with None -> () | Some prep -> do! prep
-#if ACCUMULATOR
-            let acc = Accumulator(Fold.fold, state)
-            for cmd in commands do
-                acc.Transact(interpret cmd)
-            return acc.State, acc.Accumulated }
-#else
             return interpretMany Fold.fold (Seq.map interpret commands) state }
-#endif
         let decider = resolve cartId
         let opt = if optimistic then Equinox.LoadOption.AnyCachedValue else Equinox.LoadOption.RequireLoad
         decider.Transact(interpret, opt)