bear/examples/defer_reflection.vr

// defer_reflection.vr — demonstrates the Batch-A features: `defer` cleanup,
// the `in` membership operator, `type_info()` reflection, and `range()`.
//
//   vr run examples/defer_reflection.vr

fn summarize(v) {
    // reflection: inspect any value and build a description
    let ti = type_info(v)
    let kind = ti.kind
    if ti.is_number {
        return "a number " + str(v)
    } else if ti.is_string {
        return "a string of length " + str(ti.len) + ": \"" + v + "\""
    } else if ti.is_array {
        return "an array with " + str(ti.len) + " elements"
    } else if ti.is_struct {
        return "a record with fields " + str(ti.fields)
    } else if ti.is_none {
        return "nothing"
    }
    return "a " + kind
}

fn grep_lines(docs, term) {
    // demonstrate `in` on strings + arrays, with deferred cleanup
    let matches = []
    defer println("  -> searched " + str(len(docs)) + " docs for \"" + term + "\"")
    for d in docs {
        if term in d {        // substring membership
            push(matches, d)
        }
    }
    return matches
}

fn main() {
    // range + in + type_info
    let nums = range(1, 6)    // [1, 2, 3, 4, 5]
    println("nums = " + str(nums))
    println("3 present? " + str(3 in nums))
    println("7 present? " + str(7 in nums))

    println(summarize(42))
    println(summarize("hello"))
    println(summarize([1, 2, 3]))
    println(summarize({x: 1, y: 2}))
    println(summarize(none))

    println("---")
    let docs = ["Introducing VuurRaaf", "A tiny language", "VuurRaaf: daily driver"]
    let hits = grep_lines(docs, "VuurRaaf")
    println("hits: " + str(hits))
}