In Haskell, how do you trim whitespace from the beginning and end of a string?

Question

How do you trim whitespace from the start and end of a string?

trim \"  abc \" 

=>

\"abc\"

Edit:

Ok, let me be a little cleare

Answer 1

You can combine Data.Text's strip with it's un/packing functions to avoid having overloaded strings:

import qualified Data.Text as T

strip  = T.unpack . T.strip . T.pack
lstrip = T.unpack . T.stripStart . T.pack
rstrip = T.unpack . T.stripEnd . T.pack

Testing it:

> let s = "  hello  "
> strip s
"hello"
> lstrip s
"hello  "
> rstrip s
"  hello"