REslava.ResultFlow — Mermaid pipeline diagram generator with built-in LanguageExt support

[reslava]

Hi @louthy 👋

I built a source generator called REslava.ResultFlow that auto-generates Mermaid flowchart diagrams from fluent monadic chains — and it ships with built-in support for LanguageExt (Filter, Do, DoAsync, DoLeft, DoLeftAsync) out of the box.

Add [ResultFlow] to any method using LanguageExt:

[ResultFlow]
public Either<Error, UserDto> Register(RegisterCommand cmd) =>
    Validate(cmd)
        .Filter(IsEmailValid)
        .Do(AuditLog)
        .Do(SendNotification);

The IDE code action injects the Mermaid diagram as a block comment above the method — no build required:

/*
flowchart LR
    N0_Filter["Filter"]:::gatekeeper
    N0_Filter -->|pass| N1_Do
    N0_Filter -->|fail| F0["Failure"]:::failure
    N1_Do["Do"]:::sideeffect
    N1_Do --> N2_Do
    N2_Do["Do"]:::sideeffect
    classDef gatekeeper fill:#e3e9fa,color:#3f5c9a
    classDef sideeffect fill:#fff4d9,color:#b8882c
    classDef failure fill:#f8e3e3,color:#b13e3e
*/
[ResultFlow]
public Either<Error, UserDto> Register(RegisterCommand cmd) => ...

Operations are color-coded by semantic role (gatekeeper, transform, side-effect, failure path). Any method not in the dictionary is rendered as a generic node — the diagram always generates.

For custom or additional method names, a resultflow.json file lets you extend or override the built-in classification.

• NuGet: https://www.nuget.org/packages/REslava.ResultFlow
• Docs: https://reslava.github.io/nuget-package-reslava-result/resultflow/
• GitHub: https://github.com/reslava/nuget-package-reslava-result#3--resultflow--mermaid-diagrams-autogenerated

Just wanted to share in case it's useful to LanguageExt users!

[louthy]

Nice! Thanks for sharing. When I'm back from my trip I'll add it to the community projects section of the wiki 👍