PGF Service: a bit more clever lexer=text

Only change the first word to lowercase if the original input is not found in
the grammar's morphology. This allows parsing of sentenses starting with "I" in 
English, nouns in German and proper names in other languages, but it can make
the wrong choice for multi-words.

src/runtime/haskell/PGF/Lexing.hs

@@ -2,8 +2,13 @@ module PGF.Lexing where
 import Data.Char(isSpace,toLower,toUpper)
 
 -- * Text lexing
+-- | Text lexing with standard word capitalization of the first word of every sentence
 lexText :: String -> [String]
-lexText = uncap . lext where
+lexText = lexText' uncapitInit
+
+-- | Text lexing with custom treatment of the first word of every sentence.
+lexText' :: (String->String) -> String -> [String]
+lexText' uncap1 = uncap . lext where
   lext s = case s of
     c:cs | isMajorPunct c -> [c] : uncap (lext cs)
     c:cs | isMinorPunct c -> [c] : lext cs
@@ -11,7 +16,7 @@ lexText = uncap . lext where
     _:_ -> let (w,cs) = break (\x -> isSpace x || isPunct x) s in w : lext cs
     _ -> [s]
   uncap s = case s of
-    (c:cs):ws -> (toLower c : cs):ws
+    w:ws -> uncap1 w:ws
     _ -> s
 
 unlexText :: [String] -> String
@@ -78,6 +83,11 @@ capitInit s = case s of
   c:cs -> toUpper c : cs
   _ -> s
 
+-- | Uncapitalize first letter
+uncapitInit s = case s of
+  c:cs -> toLower c : cs
+  _ -> s
+
 -- | Unquote each string wrapped in double quotes
 unquote = map unq where 
   unq s = case s of