Here's a code fragment I have from working with Hal Daume's "Yet Another
Haskell Tutorial". I cannot figure out how to iterate over the result
from askForNumbers that returns "IO [Integer]", and print them.
The "<-" operator seems to take IO off of the results from actions like
getContents, which returns type "IO String", but I cannot seem to use it
to take IO off of lists with it. What am I supposed to do?
Also, as a side question, what should I be returning from the do function?
>>>code>>>>
module Main
where
import IO
main = do
hSetBuffering stdin LineBuffering
s <- askForNumbers {-- This compiles --}
map show s {-- But this doesn't. Why? --}
{-- What expression should I be returning from
do? --}
askForNumbers = do
putStrLn "Give me a number (or 0 to stop):"
guess <- getLine
let number = read guess
if number == 0
then return []
else do
rest <- askForNumbers
return (number : rest)
<<<code<<<<
Thanks in advance.
Taro Ikai
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