public struct Uniform { var base: RandomNumberGenerator init(base: RandomNumberGenerator) { self.base = base } /// Returns a value from uniform [low, high) distribution. public mutating func next(low: Float, high: Float) -> Float { let uint32: UInt32 = base.next() return (high - low) * (Float(bitPattern: uint32 >> 9 | 0x3f80_0000) - 1) + low } } extension RandomNumberGenerator { public var uniform: Uniform { return Uniform(base: self) } }

こういうの作ろうと思ったんですがRNGがstructだと内部状態コピーされるから微妙ですね…… (edited)