Rewrote null to check the empty string

Author: Risto-Stevcev

src/Data/String.purs

@@ -36,7 +36,6 @@ module Data.String
 import Prelude
 
 import Data.Maybe (Maybe(..), isJust)
-import Data.Monoid (mempty)
 import Data.String.Unsafe as U
 
 -- | Returns the character at the given index, if the index is within bounds.
@@ -73,7 +72,7 @@ foreign import _toChar :: (forall a. a -> Maybe a)
 
 -- | Returns `true` if the given string is empty.
 null :: String -> Boolean
-null = eq mempty
+null s = s == ""
 
 -- | Returns the first character and the rest of the string,
 -- | if the string is not empty.