[Haskell-beginners] How to remove leading and trailing non-alpha characters, and multiple consecutive spaces?

[David Virebayre]

How about

import qualified Data.Text as T
import Data.Char

let s="   \"    John      Doe-Smith    \"    "
T.unpack . T.unwords . T.words . T.dropWhileEnd (not. isAlpha) .
T.dropWhile (not . isAlpha) . T.pack $ s

"John Doe-Smith"


Cheers,

David.


2013/6/7 Michael Peternell <michael.peternell at gmx.at>:
> Hi,
>
> how about
>
> import Data.Char
> let input = " 'John   Doe-Smith' $"
> unwords.words $ reverse . dropWhile (not.isAlpha) . reverse $ dropWhile (not.isAlpha) input
> Result: "John Doe-Smith"
>
> -Michael
>
> Am 07.06.2013 um 00:36 schrieb "Costello, Roger L." <costello at mitre.org>:
>
>> Hi Folks,
>>
>> I have a string that contains a person's name.
>>
>> Prior to the person's name there may be some non-alpha characters.
>>
>> After the person's name there may be some non-alpha characters.
>>
>> Between the person's first name and last name there should be only one space.
>>
>> I want to remove the leading and trailing non-alpha characters and remove the extra spaces.
>>
>> Here is an example string:
>>
>> s = "     \"    John     Doe    \"    "
>>
>> After processing, I should have:
>>
>>       John Doe
>>
>> Below is my implementation. Is there is a shorter and more efficient implementation?
>>
>> ----------------------------------
>> import Data.Char
>> import Data.List
>>
>> s = "     \"    John     Doe    \"    "
>>
>> -- remove leading non-alpha characters
>>
>> t1 = dropWhile (not . isAlpha) s              -- returns "John     Doe    \"    "
>>
>> -- break the string up into a list of words,
>> -- delimited by white space
>>
>> t2 = words t1                         -- returns ["John","Doe","\""]
>>
>> -- create a string consisting of the first
>> -- name, space, last name
>>
>> t3 = t2!!0 ++ " " ++ t2!!1            -- returns "John Doe"
>>
>> -- Put it all together:
>>
>> t4 = ((words . dropWhile (not . isAlpha)) s)!!0 ++ " " ++ ((words . dropWhile (not . isAlpha)) s)!!1
>>
>>
>>
>> _______________________________________________
>> Beginners mailing list
>> Beginners at haskell.org
>> http://www.haskell.org/mailman/listinfo/beginners
>
>
> _______________________________________________
> Beginners mailing list
> Beginners at haskell.org
> http://www.haskell.org/mailman/listinfo/beginners