Just use this rule of thumb. If it is a monad (like IO Int, IO
String) use do - notation. If it isn't a monad (like Int, String),
just use let syntax, same as you did with the first list.
main = do
let ttime = [8,20,10,15]
a = dauer ttime (OPTIONAL let a = dauer ttime)
putStrLn a
On Sun, Mar 4, 2012 at 1:41 PM, Kevin Clees k.cl...@web.de wrote:
Dear Haskell programmers,
I'm very confused, because I really don't know how to handle with IO's and
other datatypes, such as Int or String.
If I want to build a haskell program can I only use IO() method outputs ?
How can I give a Int result from a different method back to the main?
Would this mean that I have to create only IO() outputs? Is this correct?
For example:
-- A User has to choose something, so I need a IO() datatype
main :: IO()
main = do
[...]
let listtournementTime = [8,20,10,15]
-- This is wrong: Couldn't match expected type `IO t0' with actual type
`Int'
-- The results of the method dauer is a Int. Do I have to transform the
method to an IO() Output
a - Dauer listtournementTime
[...]
-- the methods
dauer:: [Int] - Int
dauer (x:xs)
| laenge(x:xs) == 1 = 0
| mod (laenge (x:xs)) 2 == 0 = (tmp x xs) + dauer xs
| mod (laenge (x:xs)) 2 /= 0 = dauer xs
| otherwise = 99 -- failure
tmp:: Int - [Int] - Int
tmp y (x:xs) = x-y
laenge :: [a] - Integer
laenge [] = 0
laenge (x:xs) = 1 + laenge xs
The last three methods are working correct, if I directly put some data into
the methods, like:
dauer [10,15]
===Result=== 5
Thank you for any help
Best greetings from Namibia
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
