Array Init

Prefer using Array(seq) over seq.map { $0 } to convert a sequence into an Array

• Identifier: array_init
• Enabled by default: No
• Supports autocorrection: No
• Kind: lint
• Analyzer rule: No
• Minimum Swift compiler version: 5.0.0
• Default configuration:

  Key	Value
  severity	warning

Rationale

When converting the elements of a sequence directly into an Array, for clarity, prefer using the Array constructor over calling map. For example

Array(foo)

rather than

foo.↓map({ $0 })

If some processing of the elements is required, then using map is fine. For example

foo.map { !$0 }

Constructs like

enum MyError: Error {}
let myResult: Result<String, MyError> = .success("")
let result: Result<Any, MyError> = myResult.map { $0 }

may be picked up as false positives by the array_init rule. If your codebase contains constructs like this, consider using the typesafe_array_init analyzer rule instead.

Non Triggering Examples

Array(foo)

foo.map { $0.0 }

foo.map { $1 }

foo.map { $0() }

foo.map { ((), $0) }

foo.map { $0! }

foo.map { $0! /* force unwrap */ }

foo.something { RouteMapper.map($0) }

foo.map { !$0 }

foo.map { /* a comment */ !$0 }

Triggering Examples

foo.↓map({ $0 })

foo.↓map { $0 }

foo.↓map { return $0 }

foo.↓map { elem in
    elem
}

foo.↓map { elem in
    return elem
}

foo.↓map { (elem: String) in
    elem
}

foo.↓map { elem -> String in
    elem
}

foo.↓map { $0 /* a comment */ }

foo.↓map { /* a comment */ $0 }