gistfile1.txt

let infinite-range =
    Generator
        inline () 0
        inline (x) true
        inline (x) x
        inline (x) (x + 1)

inline zip (a b)
    let start-a valid-a at-a next-a = ((a as Generator))
    let start-b valid-b at-b next-b = ((b as Generator))
    let start-a... = (start-a)
    let lsize = (va-countof start-a...)
    let start... = (va-va-append start-b start-a...)
    Generator
        inline () start...
        inline (it...)
            let it-a it-b = (va-split lsize it...)
            (valid-a (it-a)) & (valid-b (it-b))
        inline (it...)
            let it-a it-b = (va-split lsize it...)
            va-va-append (inline () (at-b (it-b))) (at-a (it-a))
        inline (it...)
            let it-a it-b = (va-split lsize it...)
            va-va-append (inline () (next-b (it-b))) (next-a (it-a))

inline enumerate (x)
    zip infinite-range x