该类型有多少个不同的值？

Question

我有一个给定的类型

type Foo = Either (Bool, ()) (Maybe Ordering)

我知道该类型Bool有两个不同的值：True和False。

假设，以下类型是否正确：

type Foo = Either (Bool, ()) (Maybe Ordering)

2+2+1+2+3 = 10考虑到其他类型的构建方式，具有不同的值：

data Either a b = Left a | Right b
data Maybe a = Just a | Nothing
data Ordering = EQ | LT | GT

Answer 1

你有什么：

        type Foo = Either (Bool, ()) (Maybe Ordering)

Either 携带一种类型的值，或另一种类型的值：

data Either a b = Left a | Right b
    |Either a b|  =  |a| + |b|

        |Foo| = |(Bool, ())| + |Maybe Ordering|

(,)携带两个值，每个值都有对应的类型，因此对于每个特定a类型的值，都有特定类型值的|b|选择b：

data (,) a b = (a , b)
    |(a,b)| = |a| * |b|

        |Foo| = |Bool| * |()| + |Maybe Ordering|

Bool就像Either () ()：

data Bool = False | True
    |Bool|  =  1  +  1 

        |Foo| = (1 + 1) * |()| + |Maybe Ordering|

()只有一个值，()：

data () = ()
    |()| = 1

        |Foo| = (1 + 1) * 1  +  |Maybe Ordering|

Maybe a就像Either () a：

data Maybe a = Nothing | Just a
    |Maybe a|   =   1  +  |a|

        |Foo| = (1 + 1) * 1  +  (1 + |Ordering|)

Ordering就像Either () (Either () ())：

data Ordering = EQ | LT | GT
    |Ordering| = 1 +  1 +  1

        |Foo| = (1 + 1) * 1  +  (1 + (1 + 1 + 1))

你做数学。:)