/////// Y-combinator function (for single-argument lambdas) ///////

y @FN [f]
{ @( x -> { @f (z -> {@(@x x) z}) } )   // output of this expression is treated as a verb, due to outer @(  )
   ( x -> { @f (z -> {@(@x x) z}) } )   // this is the argument supplied to the above verb expression
};


/////// Function to generate an anonymous factorial function as the return value -- (not tail-recursive) ///////

fact_gen @FN [f]
{ n -> { (n<=0) ? {1} {n * (@f n-1)}
       }
};


/////// Function to generate an anonymous fibonacci function as the return value -- (not tail-recursive) ///////

fib_gen @FN [f]
{ n -> { (n<=0) ? { 0                                    }
                  { (n<=2) ? {1} { (@f n-1) + (@f n-2) } }
       }
};


/////// loops to test the above functions ///////

@VAR factorial = @y fact_gen;
@VAR fibonacci = @y fib_gen;

@LOOP init:{@VAR i = -1} while:(i <= 20) next:{i++}
{ @SAY  i "factorial =" (@factorial i) };

@LOOP init:{     i = -1} while:(i <= 16) next:{i++}
{ @SAY "fibonacci<" i "> =" (@fibonacci i) };