Haskell无法将期望的类型“ Double”与实际类型“ Int”匹配

Question

This is the code of my program:

funct :: Double -> Double
funct x = 3/(x^2+1)

zetaRange :: (Int, Int) -> [Double]
zetaRange (x,y) = [ 0.01 * funct n | n <- [x..y] ]

and error, which I'm getting:

Couldn't match expected type 'Double' with actual type 'Int'

In the first argument of 'funct', namely 'n'

In the second argument of '(*)', namely 'funct n'

I really newbie to haskell, so trying to fix this error wasn't successful. funct is returning Double, so I can't understand why error says that it's actual type is Int. Please, help!

Answer 1

您需要将Int n转换为Double ：

zetaRange (x,y) = [ 0.01 * funct (fromIntegral n) | n <- [x..y] ]