Re: how to convert IO String to string
At 2002-11-22 08:12, Lu Mudong wrote:
hi, all, I'm having problem convert IO String to string, I read a file, and it's an IO String,
Right,
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. -- Ashley Yakeley, Seattle WA
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
participants (2)
-
Ahn Ki-yung -
Ashley Yakeley