Handling recursive syntax using def throws StackOverflowException

[tusharmath]

Parsing something like this —

FOO
[FOO
[[FOO]]
[[[FOO]]]

In the above syntax, FOO can be wrapped any number of times inside a square bracket.
The parser is implemented using the following code —

val foo = Syntax.string("FOO", "foo")

def wrappedN(foo: Syntax[String, Char, Char, String]): Syntax[String, Char, Char, String] = {
  val wrapped = foo.between(Syntax.char('['), Syntax.char(']'))
  wrapped | wrappedN(wrapped)
}

val syntax = wrappedN(foo)

val input = "[[FOO]]"

println(syntax.parseString(input)) // Stack overflow exception

Failing Test: https://github.com/zio/zio-parser/pull/115/files

Update 1:
Using a lazy val instead of a def works properly.

lazy val syntax: Syntax[String, Char, Char, Unit] =
  (
    Syntax.string("FOO", {}) | syntax
  ).between(Syntax.char('['), Syntax.char(']'))