batch A

examples/defer_reflection.vr

@@ -0,0 +1,53 @@
+// 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))
+}

examples/tests.vr

@@ -658,6 +658,83 @@ fn test_flag_parsing() {
 	assert len(flag_positional()) == 0
 }
 
+fn test_defer_cleanup() {
+	// defer runs on every exit path; its effect is visible to the caller via
+	// the shared mutable array (arrays are references).
+	let log = []
+	let a = defer_probe(log, 1)
+	assert a == 0
+	assert len(log) == 2
+	assert log[0] == "open"
+	assert log[1] == "close"
+}
+
+fn defer_probe(log, mode) {
+	push(log, "open")
+	defer push(log, "close")
+	if mode == 0 {  // early return path also runs defer
+		return 9
+	}
+	return 0
+}
+
+fn test_defer_lifo() {
+	// defers run in reverse declaration order (LIFO), all before returning
+	let logA = []
+	let r = defer_lifo(logA)
+	assert r == 0
+	assert len(logA) == 2
+	assert logA[0] == "2nd-registered"
+	assert logA[1] == "1st-registered"
+}
+
+fn defer_lifo(log) {
+	defer push(log, "1st-registered")
+	defer push(log, "2nd-registered")
+	return 0
+}
+
+fn test_in_operator() {
+	let arr = [1, 2, 3]
+	assert 2 in arr
+	assert 9 in arr == false
+	let m = {x: 1}
+	assert "x" in m
+	assert "zzz" in m == false
+	let s = "hello world"
+	assert "world" in s
+	assert "nope" in s == false
+	assert not (9 in arr)
+}
+
+fn test_range_helper() {
+	let up = range(0, 4)
+	assert len(up) == 4
+	assert up[0] == 0
+	assert up[3] == 3
+	let down = range(3, 0)
+	assert down[0] == 3
+	assert down[2] == 1
+	assert len(down) == 3
+}
+
+fn test_type_info() {
+	let ti = type_info(42)
+	assert ti.kind == "int"
+	assert ti.is_int == 1
+	assert ti.is_number == 1
+	let ts = type_info("xyz")
+	assert ts.is_string == 1
+	assert ts.len == 3
+	let tn = type_info(none)
+	assert tn.kind == "none"
+	assert tn.is_none == 1
+	let to = type_info({a: 1})
+	assert to.is_struct == 1
+	assert len(to.fields) == 1
+	assert to.fields[0] == "a"
+}
+
 fn test_failing() {
 	// this one is meant to fail — shows up in `vr test` output
 	assert 1 == 2