如何使类型成为Eq的实例

Question

我有一个名为的数据类型Praat.我想Praat成为一个实例,Eq以便两个Praats相等,当且仅当mx它们相等时.怎么做到这一点？

-- data type
data Praat t = Praat [k] [(k,k,k,k)] 

-- praat gives the maximum frequency
Praat t -> Int
mx (Praat [] _) = 0
mx (Praat (e:es) pt) = ...........

这就是我试图定义实例但它无法正常工作的方式.

-- I want to make Praat instance of Eq so that two Praat are equal
-- when their respective `mx` are equal
instance Eq Praat where
   mx :: (Praat k)->Int
   (mx k) == (mx k) = True
   _ == _ = False

Answer 1

instance Eq Praat where
    x == y = mx x == mx y

这几乎是你所说的直接翻译.x等于y什么时候mx x == mx y.