Memory by Example

Value Semantics

Assignment creates another name for the same value, not a mutable reference to be changed through either name.

original: List[Int] = [1, 2]
snapshot: List[Int] = original

Arc/cow

ARC and copy-on-write let containers share storage until an update would be observable.

updated: List[Int] = alias.append(3)
-- original is still [1, 2]

Aliases

append through one name returns a new list value; the earlier alias keeps seeing the original list.

a: List[Int] = [1]
b: List[Int] = a
c: List[Int] = b.append(2)

Closure Capture

Closures capture values, not mutable variables by reference, which keeps cross-task captures safe.

pure func make_adder(base: Int) -> pure (Int) -> Int:
    pure func(x): x + base

Example

pure func make_label(prefix: String) -> pure (Int) -> String:
	pure func(n: Int): prefix + n.to_string()


func main(args: List[String]) -> Void:
	original: List[Int] = [1, 2, 3]
	snapshot: List[Int] = original
	updated: List[Int] = snapshot.append(4)

	label = make_label("count: ")
	print(original
			.length()
			.to_string())
	print(updated
			.length()
			.to_string())
	print(label(updated.length()))

Try It

blorp run memory.brp