I am trying to make a program that reads a number given by a user and then prints it. the number has to be an integer when I print it, but this code gives me a parse error:
main = do
{
putStrLn "Please enter the number"
number <- getLine
putStrLn "The num is:" ++ show (read number:: Int)
}
If you use brackets in your do statement, you have to use semicolons. Also, the last line should be putStrLn $ "The num is:" ++ show (read number :: Int)
So you have two options:
main = do
{
putStrLn "Please enter the number";
number <- getLine;
putStrLn $ "The num is:" ++ show (read number:: Int)
}
or:
main = do
putStrLn "Please enter the number"
number <- getLine
putStrLn $ "The num is:" ++ show (read number:: Int)
Almost all of the code I've seen uses the second version, but they are both valid. Note that in the second version, whitespace becomes significant.
readLn :: IO Int instead of getLine. In this snippet, there is not enough information to infer it's a number without specifying it somewhere; if you actually did some numeric stuff with it, you'd be able to use readLn by itself.