dotnet/fsharp

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The F# compiler, F# core library, F# language service, and F# tooling integration for Visual Studio

Stars: 4.3k
Forks: 876
Open beginner issues: 0
Indexed issues: 1.1k
Avg merge: 4d 22h
Merged PRs (30d): 144

Dominant language: F#
License: MIT
Last GitHub push: Sep 14, 2026
Latest indexed: Sep 15, 2026
Contributing guide: Contributing guide
Code of conduct: Code of conduct
Beginner labels: help wanted good first issue

Open All

1129 open issues indexed

Inlining in CEs is prevented by DU constructor in the CE block Open

Area-Compiler-CodeGen Area-ComputationExpressions Bug

dotnet/fsharp#18753 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
while ... do: inconsistent handling of whitespace / indentation Open

Area-Compiler-Syntax Feature Improvement

dotnet/fsharp#18754 · 6 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Spurious casual type parameters on a method Open

Area-Compiler-SigFileGen Bug Theme-Simple-F#

dotnet/fsharp#18760 · 0 comments · 1 reaction · 0 assignees · Indexed Sep 15, 2026
`UnusedOpensAnalyzer` is constantly executed even then disabled causing VS unresponsiveness Open

Area-VS-Editor Bug Impact-Medium

dotnet/fsharp#18762 · 21 comments · 1 reaction · 0 assignees · Indexed Sep 15, 2026
[<TailCall>] attribute gives incorrect warning in many examples Open

Area-Compiler-Optimization Area-Diagnostics Bug

dotnet/fsharp#18780 · 14 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
VS: F12 Go to definition sometimes goes to the top of the file instead of the symbol Open

Area-VS-Editor Bug

dotnet/fsharp#18799 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Confusing use of ticks in FS0064 warning. Open

Theme-Simple-F#

dotnet/fsharp#18810 · 11 comments · 1 reaction · 0 assignees · Indexed Sep 15, 2026
Can't define extensions for two same named types in a single module Open

Area-Compiler-CodeGen Bug

dotnet/fsharp#18815 · 0 comments · 3 reactions · 0 assignees · Indexed Sep 15, 2026
Tests: flaky "core/printing" tests Open

Contributor Pain

dotnet/fsharp#18839 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 15, 2026
`///` comments on the same line as a DU case apply to the next case Open

Area-Compiler-Syntax Bug Impact-Medium

dotnet/fsharp#18843 · 5 comments · 1 reaction · 0 assignees · Indexed Sep 15, 2026
Null reference exception when nesting loops in Release mode (TaskSeq) Open

Area-Compiler-StateMachines Bug

dotnet/fsharp#18848 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 15, 2026
A wrong type is reported in a type mismatch error Open

Bug good first issue help wanted

dotnet/fsharp#18849 · 7 comments · 1 reaction · 0 assignees · Indexed Sep 15, 2026
Null reference exception related to tuples in union types in Release mode (TaskSeq) Open

Area-Compiler-StateMachines Bug

dotnet/fsharp#18853 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Error when using `[<OptionalArgument>]` with caller information attributes in delegate definitions Open

Area-Compiler-CodeGen Bug

dotnet/fsharp#18868 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Single line list with `if` doesn't obey published operator precedence with `;` Open

Area-Compiler-Syntax Feature Improvement

dotnet/fsharp#18870 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Tooling suggestion - set up a path to deprecate non-SDK style projects (classic msbuild projects) Open

Area-VS-Editor Feature Request

dotnet/fsharp#18896 · 0 comments · 1 reaction · 0 assignees · Indexed Sep 15, 2026
StackOverflow typecheking code with some SRTPs Open

Area-Compiler-Checking Area-Compiler-SRTP Area-Compiler-StateMachines Bug

dotnet/fsharp#18901 · 0 comments · 1 reaction · 0 assignees · Indexed Sep 15, 2026
Wrong actual type is captured in diagnostic Open

Bug Needs-Triage

dotnet/fsharp#18905 · 1 comment · 1 reaction · 0 assignees · Indexed Sep 15, 2026
TypeLoadException when accessing CustomAttributeData.ConstructorArguments in fsi Open

Area-FSI Bug Impact-Medium

dotnet/fsharp#18922 · 2 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Implicit Action/Func conversion captures extra expressions Open

Area-Compiler-CodeGen Area-Diagnostics Bug

dotnet/fsharp#18953 · 3 comments · 1 reaction · 0 assignees · Indexed Sep 15, 2026
AOT compilation warnings cannot be pinpointed in code Open

Area-AOT Feature Improvement

dotnet/fsharp#18959 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Calling a generic method during object construction incorrectly constrains the generic to a type Open

Area-Compiler-Checking Bug

dotnet/fsharp#18967 · 2 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Inline methods break in types with self identifier with misleading error message Open

Area-Compiler-Checking Bug

dotnet/fsharp#18974 · 2 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Non deterministic edge case with parallel reference resolution Open

dotnet/fsharp#18977 · 2 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
dotnet fsi command line: -- has no effect Open

Area-FSI Bug

dotnet/fsharp#18983 · 1 comment · 1 reaction · 0 assignees · Indexed Sep 15, 2026
Contributor QoL - .fsproj hacks to build ComponentTests for a single-file test run fast? Open

Contributor Pain Feature Request

dotnet/fsharp#19011 · 2 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
net10.0: Support MethodImpl.Async Open

Area-Compiler-ImportAndInterop Feature Request

dotnet/fsharp#19056 · 9 comments · 6 reactions · 0 assignees · Indexed Sep 15, 2026
Using computation builder `TryWith` with a non-`Exception` parameter generates invalid IL Open

Area-ComputationExpressions Bug

dotnet/fsharp#19061 · 8 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
CLR Crashes when running program, which uses constrained calls Open

Area-Compiler-CodeGen Area-Compiler-SRTP Bug

dotnet/fsharp#19075 · 2 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
VS: Installing custom built vsix does not update the tools Open

Needs-Triage

dotnet/fsharp#19077 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Breakpoint on `()` in if branch in async CE not hit Open

Area-Debug Bug

dotnet/fsharp#19094 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Cannot wait on monitors on this runtime Open

Bug Needs-Triage

dotnet/fsharp#19110 · 5 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Invitation to F# Projects Maintainers: Join the Compiler Regression Testing Pilot Open

Engineering Informational

dotnet/fsharp#19126 · 5 comments · 11 reactions · 0 assignees · Indexed Sep 15, 2026
Building a large F# project is indeterminately slow Open

Bug Theme-Performance

dotnet/fsharp#19132 · 3 comments · 1 reaction · 1 assignee · Indexed Sep 15, 2026
--preferreduilang appears in fsi.CommandLineArgs when run from Msbuild and .NET 10 SDK Open

Bug

dotnet/fsharp#19146 · 3 comments · 1 reaction · 0 assignees · Indexed Sep 15, 2026
Performance Regression: .NET 10.0.101 build takes 300s (was 25s in 10.0.100) Open

Bug Regression Theme-Performance

dotnet/fsharp#19165 · 18 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Performance Regression: Build takes 7s in .net9 and 5min in .net10 Open

Bug Theme-Performance

dotnet/fsharp#19169 · 7 comments · 3 reactions · 0 assignees · Indexed Sep 15, 2026
Can the F# compiler service 10 run on the net8 runtime? Open

Engineering

dotnet/fsharp#19174 · 3 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Support xmldoc `<inheritdoc>` and `<include>` Open

Area-Compiler Feature Request

dotnet/fsharp#19175 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 15, 2026
VS Editor, usability issue with tooltips disapearing too quick in VS2026. Open

Area-VS-Editor Bug Resolution-External

dotnet/fsharp#19178 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 15, 2026
IWSAM can result in a runtime verification exception Open

Area-Compiler-SRTP Bug

dotnet/fsharp#19184 · 2 comments · 1 reaction · 0 assignees · Indexed Sep 15, 2026
Partial application doesn't work well with implicit cast Open

Bug

dotnet/fsharp#19200 · 2 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
F# Intellisense eats my CPU Open

Area-Tooling Bug Needs-Verify next release

dotnet/fsharp#19212 · 3 comments · 1 reaction · 0 assignees · Indexed Sep 15, 2026
fsi incorrect handling of some script arguments Open

Area-FSI Bug

dotnet/fsharp#19214 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
No compiler error when attempting to use voidptr as type argument Open

Area-Compiler-CodeGen Bug

dotnet/fsharp#19224 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Some checks don't be performed on F#-style extension methods Open

Area-Compiler-Checking Bug

dotnet/fsharp#19227 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
BindNReturn documentation error Open

Area-Documentation Bug

dotnet/fsharp#19316 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Wrong tooltip with a type provider constructor for an unresolved reference Open

Area-LangService-ToolTips Area-TypeProviders Bug

dotnet/fsharp#19330 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Use Spekt for test result files Open

Engineering

dotnet/fsharp#19337 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Type subsumption cache causes sustained ~150% CPU in IDE with generative type providers (hash code not memoized) Open

Bug Theme-Performance

dotnet/fsharp#19368 · 16 comments · 2 reactions · 0 assignees · Indexed Sep 15, 2026

dotnet/fsharp

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