Needle.hs

-- | A string we're looking for in the source.
--
-- /Mnemonic: "needle in a haystack"/
newtype Needle = Needle Strict.Text
  deriving Eq

-- | Needles are sorted by length with the longest needles first.
--
-- We use this ordering when performing replacements. For example, if both 
-- "a" and "ab" are needles, then we give "ab" a chance to be found /before/
-- "a". Otherwise, "a" would always match first and the "ab" replacement
-- would never occur.
instance Ord Needle
  where
    compare = compare `on` \(Needle x) -> (negate (StrictText.length x), x)