In reply to @crochubourbier "or the fact that": Semantically everything
behaves like a value. For dynamic heap types like `seq` and `string` they're
hidden stack-managed fat-pointers. So every type in the language, top to bottom,
unless specifically marked `ref` or `ptr`, has a scoped lifetime, the vast
majority of functions operate on value and produce new values rather than
operating on identity or modifying in place (so they can function with
immutability by default), and it's all enforced by compiler unless you
explicitly activate the escape hatches which then very clearly marks every place
in code where reference semantics are being used.