Analysis of the Myriad plugin generators reveals that the logic for resolving a DU case identifier (optionally fully qualifying it with the parent type name when RequireQualifiedAccess is present) is duplicated between DUCasesGenerator.fs and LensesGenerator.fs.

Assignee: @copilot

Summary

DUCasesGenerator.fs defines a named helper function resolveCaseIdent that computes the full case name. LensesGenerator.fs re-implements the exact same logic inline as matchCaseIdentParts. These should be unified in GeneratorHelpers so both generators share a single implementation.

Duplication Details

Pattern: Qualified DU case name resolution

• Severity: Medium
• Occurrences: 2
• Locations:
  • src/Myriad.Plugins/DUCasesGenerator.fs (lines 18–24) — named function resolveCaseIdent
  • src/Myriad.Plugins/LensesGenerator.fs (lines 68–72) — inline matchCaseIdentParts

Code in DUCasesGenerator.fs (lines 18–24):

let resolveCaseIdent (requiresQualifiedAccess: bool) (parent: LongIdent) (id: Fantomas.FCS.Syntax.Ident) : SynLongIdent =
    let parts =
        if requiresQualifiedAccess then
            (parent |> List.map (fun i -> i.idText)) @ [id.idText]
        else
            [id.idText]
    SynLongIdent.Create parts

Equivalent inline logic in LensesGenerator.fs (lines 68–72):

let matchCaseIdentParts =
    if requiresQualifiedAccess then
        (parent |> List.map (fun i -> i.idText)) @ [id.idText]
    else
        [id.idText]
// then used as: SynLongIdent.Create matchCaseIdentParts

Impact Analysis

• Maintainability: Any change to qualified-access case resolution (e.g. supporting nested modules) must be applied in two places, risking divergence.
• Bug Risk: A fix for one generator may be missed in the other, causing inconsistent behaviour between lenses and dus generators.
• Code Bloat: Minor, but obscures the shared contract between the two generators.

Refactoring Recommendations

1. Move resolveCaseIdent to GeneratorHelpers
   • Add resolveCaseIdent (or rename to resolveDuCaseIdent) to src/Myriad.Plugins/GeneratorHelpers.fs
   • Remove the local definition from DUCasesGenerator.fs
   • Replace the inline matchCaseIdentParts block in LensesGenerator.fs with a call to the shared helper
   • Estimated effort: ~30 minutes
   • Benefits: Single source of truth for qualified-access case resolution

Implementation Checklist

• Review duplication findings
• Move resolveCaseIdent to GeneratorHelpers.fs
• Update DUCasesGenerator.fs to call the shared helper
• Update LensesGenerator.fs to call the shared helper
• Run integration tests to verify no functionality broken

Analysis Metadata

• Analyzed Files: 3 (DUCasesGenerator.fs, LensesGenerator.fs, GeneratorHelpers.fs)
• Detection Method: Semantic code analysis
• Commit: 165a7e5
• Analysis Date: 2026-03-07

Generated by Duplicate Code Detector

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