Add: Interoperable

[oscbyspro]

I'll add this protocol and extension for interoperability purposes (#73):

public protocol Interoperable {
    
    associatedtype Stdlib
    
    init(_ stdlib: consuming Stdlib)
        
    consuming func stdlib() -> Stdlib
    
}

extension Interoperable {

    @inlinable public var stdlib: Stdlib {
        mutating _read {
            let stdlib = self.stdlib()
            yield stdlib
            self = Self(stdlib)
        }
        
        mutating _modify {
            var stdlib = self.stdlib()
            yield &stdlib
            self = Self(stdlib)
        }
    }
}

[oscbyspro]

I'll conform the core integer types to it, as well as all randomness types. I'll want to conform all integer types at some point, I believe it's just a matter of getting around to implementing generic floating point conversions.

[oscbyspro]

All of the following methods generate the same machine code in -O mode:

Godbolt

public protocol Interoperable {    
    associatedtype Stdlib    
    @inlinable init(_ source: consuming Stdlib)
    @inlinable consuming func stdlib() -> Stdlib
}

extension Interoperable {
    @inlinable public var stdlib: Stdlib {
        mutating _read {
            let stdlib = self.stdlib()
            yield stdlib
            self = Self(stdlib)
        }
        
        mutating _modify {
            var stdlib = self.stdlib()
            yield &stdlib
            self = Self(stdlib)
        }
    }
}

@frozen public struct MyInt: Interoperable {
    @usableFromInline let base: Int
    @inlinable public init(_ base: Int) { self.base = base }
    @inlinable public func stdlib() -> Int { self.base }
}

func foo(a: Int, b: Int) -> (Int, Bool) {
    a.addingReportingOverflow(b)
}

func bar(a: MyInt, b: MyInt) -> (MyInt, Bool) {
    let x = a.stdlib().addingReportingOverflow(b.stdlib())
    return (MyInt(x.partialValue), x.overflow)
}

func baz(a: consuming MyInt, b: consuming MyInt) -> (MyInt, Bool) {
    let x = a.stdlib.addingReportingOverflow(b.stdlib)
    return (MyInt(x.partialValue), x.overflow)
}