On Oct 4, 2017, at 7:26 PM, Xiaodi Wu via swift-evolution
<[email protected]> wrote:
> * Remove the range-less function. Naive users often write things like
> `Int.random() % 100`, which unbeknownst to them is biased. Providing only the
> ranged interface nudges naive users toward correct usage.
>
> * Provide an "easy" way to get some random bytes instead of a random number.
> Perhaps a Data initializer that returns random-filled bytes of the requested
> length. This helps make up for the lack of a range-less function on
> FixedWidthInteger.
>
> The "easy" functions should get the best names: Int.random(in:),
> Data.random(length:), etc. The fundamental CSPRNG interface should have an
> interface that is less friendly and less discoverable.
>
> Agree, this is a very tractable set of functions for an initial
> implementation. In fact, with these primitives and maybe some shuffling and
> choosing conveniences in the stdlib, I see the remainder as useful-to-haves
> that may or may not be critical for inclusion in the stdlib vs more
> appropriate for a dedicated math library (more to follow on that thought in a
> little while).
>
> To sum up my thoughts so far in code, building on previous comments from
> others, this would be a nice set of random APIs, IMO:
>
> ```
> extension Int {
> static func random(in range: Countable{Closed}Range<Int>) -> Int
> }
Nice. Should these be initializers like:
extension Int {
init(randomIn: Countable{Closed}Range<Int>)
}
or some other spelling?
> extension Data {
> static func random(byteCount: Int) -> Data
> }
Similarly:
extension Data {
init(randomByteCount: Int)
}
>
> extension UnsafeMutableRawPointer {
> func copyRandomBytes(count: Int) throws
> }
> // This function is to be the most primitive of the random APIs, and will
> throw if there is insufficient entropy.
>
> extension UnsafeMutableRawBufferPointer {
> func copyRandomBytes() throws
> }
> // Just as UMRBP.copyBytes(from:) parallels UMRP.copyBytes(from:count:), we
> offer this convenience here.
> ```
I’m not sure what the semantics of these APIs are, but with the appropriate doc
comment they’re probably great :-)
-Chris
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