HASKELL --- 是否有删除列表中元素的函数？
HASKELL --- Is there any function to remove an element in a list?
我的问题是我有一个列表，想删除其中的一些字符串。但是当我第一次删除时就可以了。但是第二次，它删除了字符串但带回了第一个。
你知道我怎样才能避免这种情况吗？
谢谢
Prelude Data.List Data.Char> x = ["ab","cd","ef","gh"]
Prelude Data.List Data.Char> delete "ab" x
["cd","ef","gh"]
Prelude Data.List Data.Char> delete "cd" x
["ab","ef","gh"]
!!这里 "ab" 回来了，我不想要这个！！谢谢
参见 ''How to "think functional"'' here。总之，x就是x； delete "abc" x returns 新值，它不会改变现有的x.
如果你想引用这个新的值，给它一个新的名字，像这样：
> x = ["ab","cd","ef","gh"]
> x2 = delete "ab" x
> delete "cd" x2
["ef","gh"]
我的问题是我有一个列表，想删除其中的一些字符串。但是当我第一次删除时就可以了。但是第二次，它删除了字符串但带回了第一个。 你知道我怎样才能避免这种情况吗？ 谢谢
Prelude Data.List Data.Char> x = ["ab","cd","ef","gh"]
Prelude Data.List Data.Char> delete "ab" x
["cd","ef","gh"]
Prelude Data.List Data.Char> delete "cd" x
["ab","ef","gh"]
!!这里 "ab" 回来了，我不想要这个！！谢谢
参见 ''How to "think functional"'' here。总之，x就是x； delete "abc" x returns 新值，它不会改变现有的x.
如果你想引用这个新的值，给它一个新的名字，像这样：
> x = ["ab","cd","ef","gh"]
> x2 = delete "ab" x
> delete "cd" x2
["ef","gh"]