A simple LTL parser written in Swift.
let parsed = try! LTL.parse(fromString: "!F a")
print(parsed) // prints ! F a
print(parsed.nnf) // prints G ! a
print(parsed.nnf.normalized) // prints (false R ! a)
.Package(url: "https://github.com/ltentrup/LTL.git", majorVersion: 0, minor: 1)