Kurt Hutchinson wrote:
On 2/2/06, Maurício <[EMAIL PROTECTED]> wrote:
I understand those examples, but I really would like to know how to
do that with monads. I would like to ask the same question, but now with
this code:
double a = 1000;
double b = 0;
while (a != b) {
a /= 2;
cout << a; // Prints a
cin << b; // User gives a number, stored in b
};
An idiomatic approach:
example :: Double -> Double -> IO ()
example a b
| a == b = return ()
| otherwise = do
let a' = a / 2
print a'
b' <- readLn
example a' b'
main = example 1000 0
Thanks! Robert's, Chris' and yours examples solved many of my
questions. I understand I can insert modifications in IORefs (as used by
Robert and Chris) inside the loop above:
| otherwise = do
let a' = a / 2
...
modifyIORef some_ioref some_function
...
example a' b'
I wonder if I could write a generic while based on your example:
while :: (a -> IO a) -> (a -> Bool) -> IO ()
I'll probably learn something trying that.
Best,
Maurício
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