data List (a) where {
    Nil : List (a)
    Cons : a -> List (a) -> List (a)
};

data Bool () where {
    True : Bool ()
    False : Bool ()
   };

hello_world = Cons 'h' (Cons 'e' (Cons 'l' (Cons 'l' (Cons 'o' (Cons ' ' (Cons 'w' (Cons 'o' (Cons 'r' (Cons 'l' (Cons 'd' Nil)))))))))) ;

length : List (a) -> Int ;
length xs = case xs of {
    Nil => 0;
    Cons x xs => length xs;
};

head : List (a) -> a ;
head xs = case xs of {
    Cons x xs => x;
};

firstIsOne : List (Int) -> Bool () ;
firstIsOne xs = case xs of {
    Cons x xs => case x of {
            0 => True;
            _ => case xs of {
                    Cons x xs => False;
                    _ => False;
                };
            };
    _ => False;
    };

main = firstIsOne (Cons 1 Nil);

deepPat xs = case xs of {
    Cons (Nil) _ => True;
    _                 => False;
                        };