list - Haskell 与 intersect 相对（列表）

Question

我试图得到两个列表相交的“相反”：比如：

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set Difference ，它是\\来自Data.List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]