list - Haskell 与相交相反(列表)

Question

我正在尝试获取两个列表相交的“相反”:像:

let all  = [1..5]
let mask = [2,3]
let res  = ???
-- let res = all `intersect` mask <-- reverse/opposite ?
-- I want to get [1,4,5] ?

Answer 1

您正在寻找设置差异，即 Data.List 中的 \\ 运算符:

Prelude> import Data.List ((\\))
Prelude Data.List> let all  = [1..5]
Prelude Data.List> let mask = [2,3]
Prelude Data.List> all \\ mask
[1,4,5]