rangePattern.swift

precedencegroup RangePattern {
    associativity: left
    lowerThan: RangeFormationPrecedence
}
infix operator .. : RangePattern
extension Float {
    var samePrecision: Float  {
        return Float(description) ?? 0.0
    }
}

// precisions may vary for some values.
func ..<T: FloatingPoint>(f: T, r: ClosedRange<T>) -> [T] {
	guard f < r.lowerBound && f != r.lowerBound
		else { return [] }
	return sequence(first: [f, r.lowerBound]) {
		if $0.contains(where: {$0 >= r.upperBound}) { return nil }
		return $0 + [($0.last!) + (r.lowerBound - f)]
		}.map {$0}.last!
}

// same precision accross all values.
// more info: https://bugs.swift.org/browse/SR-2062
// limitation: only work for Float aka Flaot32
func ..(f: Float, r: ClosedRange<Float>) -> [Float] {
	guard f < r.lowerBound && f != r.lowerBound
		else { return [] }
	return sequence(first: [f, r.lowerBound]) {
		if $0.contains(where: {$0 >= r.upperBound}) { return nil }
		return $0 + [(($0.last!) + (r.lowerBound - f)).samePrecision]
		}.lazy.map {$0}.last!
}


1..3...10 // => [1, 3, 5, 7, 9, 11]
2..4...10 // => [2, 4, 6, 8, 10]
1..1.5...4 // => [1, 1.5, 2, 2.5, 3, 3.5, 4]
2..4.2...10 // => [2, 4.2, 6.4, 8.6, 10.8]