Re: how to convert IO String to string

Ashley Yakeley wrote:

At 2002-11-22 08:12, Lu Mudong wrote:

...

what i need is a string,

You can do the conversion with "<-", but only inside a "do" block. For instance:

myReadFile :: IO String myReadFile = ...

main = do s <- myReadFile putStrLn s

Here, s has type String.

'do' is a syntactic sugar of monadic operations. The original form can be written as main = myReadFile >>= \s -> putStrLn s and more short by eta-conversion main = myReadFile >>= putStrLn