Re: [Haskell-beginners] having trouble with helloworld style program

here... <- is good for "pulling out" a result/value out of an IO Action (after running it) let is good for the assignment of a pure functional evaluation/result Hope this is roughly correct :-) Hartmut On Mon, Aug 8, 2011 at 1:45 PM, Ertugrul Soeylemez wrote:

Sunil S Nandihalli wrote:

...

module Main where import Prelude

stringToInt::String->Int stringToInt str = read str

main = do x<-getLine y<-stringToInt x print y

It is a type problem. Using the '<-' syntax for 'stringToInt' requires that it is a monadic function (like: String -> IO Int), but it is not. Since it is not monadic, you can simply let-bind the result to a name:

do xStr <- getLine let x = stringToInt xStr print x

Or more simply:

do xStr <- getLine print (stringToInt xStr)

Greets, Ertugrul

-- nightmare = unsafePerformIO (getWrongWife >>= sex) http://ertes.de/

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