Merge pull request #284 from fsprojects/repo-assist/perf-init-remove-lazy-2026-03-2c6e1b4098c5e418

[Repo Assist] perf: remove unnecessary Lazy allocation in TaskSeq.init per iteration

Author: dsyme

global.json

@@ -0,0 +1,6 @@
+{
+  "sdk": {
+    "version": "10.0.103",
+    "rollForward": "minor"
+  }
+}

release-notes.txt

@@ -1,5 +1,9 @@
 
 Release notes:
+
+0.5.0
+    - update engineering to .NET 9/10
+
 0.4.0
     - overhaul all doc comments, add exceptions, improve IDE quick-info experience, #136, #220, #234
     - new surface area functions, fixes #208:

src/FSharp.Control.TaskSeq.SmokeTests/FSharp.Control.TaskSeq.SmokeTests.fsproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFramework>net9.0</TargetFramework>
     <TreatWarningsAsErrors>True</TreatWarningsAsErrors>
   </PropertyGroup>
 

src/FSharp.Control.TaskSeq.Test/FSharp.Control.TaskSeq.Test.fsproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFramework>net9.0</TargetFramework>
     <TreatWarningsAsErrors>True</TreatWarningsAsErrors>
   </PropertyGroup>
 

src/FSharp.Control.TaskSeq.Test/TaskSeq.Concat.Tests.fs

@@ -249,8 +249,8 @@ module SideEffect =
         let mutable i = 0
 
         taskSeq {
-            yield ResizeArray { 1..10 }
-            yield ResizeArray { 1..10 }
+            yield ResizeArray [ 1..10 ]
+            yield ResizeArray [ 1..10 ]
 
             yield
                 ResizeArray(

src/FSharp.Control.TaskSeq/TaskSeqInternal.fs

@@ -277,7 +277,6 @@ module internal TaskSeqInternal =
 
     let init count initializer = taskSeq {
         let mutable i = 0
-        let mutable value: Lazy<'T> = Unchecked.defaultof<_>
 
         let count =
             match count with
@@ -290,28 +289,13 @@ module internal TaskSeqInternal =
         match initializer with
         | InitAction init ->
             while i < count do
-                // using Lazy gives us locking and safe multiple access to the cached value, if
-                // multiple threads access the same item through the same enumerator (which is
-                // bad practice, but hey, who're we to judge).
-                if isNull value then
-                    value <- Lazy<_>.Create(fun () -> init i)
-
-                yield value.Force()
-                value <- Unchecked.defaultof<_>
+                yield init i
                 i <- i + 1
 
         | InitActionAsync asyncInit ->
             while i < count do
-                // using Lazy gives us locking and safe multiple access to the cached value, if
-                // multiple threads access the same item through the same enumerator (which is
-                // bad practice, but hey, who're we to judge).
-                if isNull value then
-                    // TODO: is there a 'Lazy' we can use with Task?
-                    let! value' = asyncInit i
-                    value <- Lazy<_>.CreateFromValue value'
-
-                yield value.Force()
-                value <- Unchecked.defaultof<_>
+                let! result = asyncInit i
+                yield result
                 i <- i + 1
 
     }