Fuck yeah, Prolog!

good-enough(Guess, Value) :- abs(Guess**2 - Value) < 0.000001 .

improve-guess(Guess, Value, NewGuess) :- NewGuess is (Guess + (Value/Guess))/2 .

guess-root(Value, Guess, Result) :-
  good-enough(Guess, Value) -> Result is Guess;
  improve-guess(Guess, Value, NewGuess),
  guess-root(Value, NewGuess, Result).

sqrt(X, Y) :- guess-root(X, 1, Y).

>>10
Don't be threatened by Haskell's superiority, nigger. Just accept your little pet language, whatever it is, is shit next to Haskell, and make the switch.