任何人都可以帮助我吗?我正在尝试编写一个函数来检查 x 是否为奇数,而不使用奇数函数。像这样它不起作用,但我不知道为什么。
ugerade :: Integral a => a -> Bool
ugerade x
|x elem oddList = True
|otherwise = False
where
oddList=[x | x<-[1,3..]]
错误
Could not deduce (Num t0) arising from the literal ‘1’
from the context (Integral a)
bound by the type signature for ugerade :: Integral a => a -> Bool
at /Users/Mauritius/Desktop/Haskell/u02/2-2/funktionen.hs:24:11-33
The type variable ‘t0’ is ambiguous
Relevant bindings include
oddList :: [t0]
(bound at /Users/Mauritius/Desktop/Haskell/u02/2-2/funktionen.hs:29:4)
Note: there are several potential instances:
instance Integral a => Num (GHC.Real.Ratio a)
-- Defined in ‘GHC.Real’
instance Num Integer -- Defined in ‘GHC.Num’
instance Num Double -- Defined in ‘GHC.Float’
...plus three others
In the expression: 1
In the expression: [1, 3 .. ]
In a stmt of a list comprehension: x <- [1, 3 .. ]