Take - Haskell problems within lists

Question

I am in the process of learning Haskell. I have a function that looks as follows:

takeN :: Integral a => a -> [a]
takeN n = take n [x | x<-[0..]]

All I want this to do, is return n amount of elements in an infinite list, and I am unaware of why this is not working. Any explanations of how to fix it without abandoning my binding (?)

Answer 1

The reason this doesn't work is that take has the type Int -> [a] -> [a] . The number must be an Int , and can't be any Integral .

You can address the issue with fromIntegral :

takeN :: Integral a => a -> [a]
takeN n = take (fromIntegral n) [x | x<-[0..]]

Answer 2

您可以在不使用自己的功能的情况下执行此操作：输入>>取3 [1 ..]输出>> [1,2,3]