[erlang-questions] newbie question of if guards
Sun Dec 10 22:55:49 CET 2006
I'm probably missing the obvious, but I can't figure out how to use the
value of a function as a condition within an if construct. In the
sqrt_iter function below, the compiler gives me an illegal guard error -
where good_enough is a function that returns a boolean.
square(X) -> X * X.
good_enough(Guess, X) -> abs(square(Guess) - X) < 0.001.
average(X, Y) -> (X + Y) / 2.
improve(Guess, X) -> average(Guess, X / Guess).
sqrt_iter(Guess, X) ->
(good_enough(Guess, X)) -> Guess;
true -> sqrt_iter(improve(Guess, X), X)
The example should be familiar as I'm trying to translate the examples
from SICP into a number of programming languages. I'd like to get a lot
further along in Erlang.
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