• I’m not sure of the difference between #3 (one-based) and #4. And you forgot

    // composed in the comment, will require hours of tinkering in a playground, except playgrounds are broken in 7.0b2.

    • #3 uses Array style specifically for generics.

  • I personally like let doubleArray: [Double] = []

  • Squirrel (lovely reference) was my second choice, [Double]() my first.