[Haskell-beginners] IO operations

[Tobias Brandt]

Hey Alexander,

|dict| has type |String|. Therefore, |x| is of type |Char|, but |elem 
'-'| is of type |[Char] -> Bool| (simplified). Hence, you get a type 
mismatch. If you just want to count every character except |'-'|, then 
you could just you |'-' /= x|.

Cheers

Tobias

On 8/13/20 1:02 PM, Alexander Chen wrote:
> Hi,
>
> module Main where
> allwords :: IO Int
> allwords  = do
>     dict <- readFile "data/dict.txt"
>     return  $ length [x | x <- dict , not $ '-' `elem` x]
> main :: IO Int
> main = do allwords
>
> error
>
> * Couldn't match expected type `t0 Char' with actual type `Char'
> * In the second argument of `elem', namely `x'
>   In the second argument of `($)', namely '-' `elem` x
>   In the expression: not $ '-' `elem` x
>
>
> could someone tell me what I am doing wrong?
>
> thanks!
>
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