Re: [Haskell-beginners] Couldn't match expected type ‘IO ()’ with actual type [Integer]

5 Feb 2015

      Max Voit schreef op 5-2-2015 om 13:01:
...
Hi Roelof,
On Thu, 05 Feb 2015 12:37:12 +0100
Roelof Wobben  wrote:
...
main :: IO ()
main = do
     toDigits 123
src/Main.hs@14:5-14:17
Couldn't match expected type ‘IO ()’ with actual type
[Integer]
… In a stmt of a 'do' block: toDigits 123 In the expression: do
{ toDigits 123 }
since your do block consists only of one expression,
actually your main looks like:
main :: IO ()
main = toDigits 123
Perhaps this explains where the problem lies.
Considering, however, do-notation: The last statement of a do-block
needs to be an expression of the type of the do-block. Translating
do-notation to bind operator sequences[1] may be helpful in
understanding this.
best,
Max
[1] http://en.wikibooks.org/wiki/Haskell/do_notation
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Thanks,

Another question :  how can I display the array ?

putStrln works only for strings,

Roelof