FlatMap over map and reduce

Prefer flatMap over map followed by reduce([], +).

• Identifier: flatmap_over_map_reduce
• Enabled by default: Disabled
• Supports autocorrection: No
• Kind: performance
• Analyzer rule: No
• Minimum Swift compiler version: 3.0.0
• Default configuration: warning

Non Triggering Examples

let foo = bar.map { $0.count }.reduce(0, +)

let foo = bar.flatMap { $0.array }

Triggering Examples

let foo = ↓bar.map { $0.array }.reduce([], +)