F# & Configuration Architecture

F# & Configuration Architecture

This skill governs the development of the F# components (GA.MusicTheory.DSL, GA.Business.Config) and the YAML configuration architecture they support.

1. F# Coding Standards

1.1 Style & Layout

• Indent: 4 spaces.
• Naming: camelCase for values/functions, PascalCase for types/modules.
• Modules: Use module MyModule = for grouping helper functions.
• Pipelines: Prefer |> for data transformations.

1.2 Type Design

• Immutability: Use immutable records and DUs (Discriminated Unions) by default.
• CLIMutable: Add [<CLIMutable>] to records used in YAML deserialization or C# interop.
• Options: Use Option<'T> for nullability.

type TuningInfo = { Name: string; Tuning: string }

module TuningHelpers =
    let formatTuning t = $"%s{t.Name}: %s{t.Tuning}"

2. Configuration Architecture (YAML)

All static domain data (Scales, Instruments, Voicings) is stored in YAML in GA.Business.Config.

2.1 YAML Schema Rules

• Naming: Keys must be PascalCase (e.g., IntervalClassVector, ModalFamilies).
• Structure: Hierarchical data preferred.
• Serialization: Handled by YamlDotNet.

2.2 Loading Pattern

Use the standard loader pattern found in InstrumentsConfig.fs or ModesConfig.fs:

1. Define DTOs: Create CLIMutable records matching the YAML structure.
2. Locate File: Check multiple locations (Bin, Repo Root, Config subfolder) to support Test vs Run environments.
3. Deserialize: Use DeserializerBuilder().WithNamingConvention(PascalCaseNamingConvention.Instance).
4. Fallback: Always provide a minimal hardcoded fall back if the file is missing to prevent crash-loops.

let private loadData () =
    try
        let yaml = File.ReadAllText(path)
        deserializer.Deserialize<MyConfig>(yaml)
    with _ ->
        defaultData // Fallback

3. C# Interop (The Bridge)

3.1 Handling Results

Convert F# Result<'T, 'Error> to C# logic:

var result = service.DoWork();
if (result.IsOk) { ... result.ResultValue ... }