> Clauses within clauses are not "recursive", no more than "let x = 1 in (let y = 2 in (let z = 3 in x + y + z)" represents recursion in some hypothetical progr

> Clauses within clauses are not "recursive", no more than "let x = 1 in (let y = 2 in (let z = 3 in x + y + z)" represents recursion in some hypothetical programming language. But that is an example of a recursive context free grammar. The parser needs to use a stack or be defined recursively to parse things like that.