[Haskell-cafe] 回复： Replace list item with list.

[David Lilue]

There is a function "concatMap" to simplify "concat $ map".

Furthermore, you could use inline notation as follow:

concatMap (\x -> x == "z" then B else [x]) A

On Sat, Nov 4, 2017 at 7:50 AM, Денис Мирзоев <nolane16 at gmail.com> wrote:

> If you sure "z" is the last element of A you can use
>
> init A ++ B
>
> if it's somwhere in the middle consider
>
> cocat $ map f A
>   where
>     f x
>       | x == "z" = B
>       | otherwise = [x]
>
> On Sat, Nov 4, 2017 at 2:41 PM, Денис Мирзоев <nolane16 at gmail.com> wrote:
>
>> If you sure "z" is the last element of A you can use
>>
>> init A ++ B
>>
>> if it's somwhere in the middle consider
>>
>> cocat $ map f A
>>   where
>>     f x
>>       | x == "z" = B
>>       | otherwise = [x]
>>
>> On Sat, Nov 4, 2017 at 1:57 PM, FlyingSheep <flyingsheep at qq.com> wrote:
>>
>>> (take 2 A) ++ B
>>>
>>> ------------------
>>> 李 鹏
>>> 四川大学计算机学院
>>>
>>>
>>>
>>> ------------------ 原始邮件 ------------------
>>> *发件人:* "mirone"<saul-mirone at qq.com>;
>>> *发送时间:* 2017年11月4日(星期六) 晚上6:48
>>> *收件人:* "haskell-cafe"<haskell-cafe at haskell.org>;
>>> *主题:* [Haskell-cafe] Replace list item with list.
>>>
>>> Hello everyone!
>>> If I have a list A : ["x", "y", "z"]
>>> and a list B: ["f", "g"].
>>> Here is my question:
>>> What's the simplest way to replace "z" in the list A by list B, and get
>>> ["x", "y", "f", "g"] ?
>>>
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>>
>>
>
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ᐧ
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