hw12: exercise 4

[yorgey.git] / hw7 / JoinList.hs

diff --git a/hw7/JoinList.hs b/hw7/JoinList.hs
index 7a353cded5f694c8e7fc606a1258bc8d8d86142a..58d1c9f8efc22f51627a3b02fab0fae0a85edb01 100644 (file)
--- a/hw7/JoinList.hs
+++ b/hw7/JoinList.hs
@@ -1,14 +1,25 @@
 {-# OPTIONS_GHC -Wall #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE TypeSynonymInstances #-}
+
 module JoinList where
 
 import Data.Monoid
 import Sized
+import Scrabble
+import Buffer
+import Editor
 
 data JoinList m a = Empty
                   | Single m a
                   | Append m (JoinList m a) (JoinList m a)
                     deriving (Eq, Show)
 
+jlToList :: JoinList m a -> [a]
+jlToList Empty = []
+jlToList (Single m a) = [a]
+jlToList (Append m lt rt) = jlToList lt ++ jlToList rt
+
 -- exercise 1
 tag :: Monoid m => JoinList m a -> m
 tag (Empty) = mempty
@@ -42,10 +53,11 @@ dropJ _ Empty = Empty
 dropJ n v@(Single _ _) | n == 0 = v
                        | otherwise = Empty
 dropJ n (Append t l r) | n > getSize (size t) = Empty
-                       | n > (getSize (size (tag l))) =
-                           dropJ (n - getSize (size (tag l))) r
+                       | n > leftSize =
+                           dropJ (n - leftSize) r
                        | otherwise = let lft = dropJ n l in
                                      Append ((tag lft) `mappend` (tag r)) lft r
+                       where leftSize = getSize . size . tag $ l
 
 -- 3. take
 takeJ :: (Sized b, Monoid b) =>
@@ -56,7 +68,49 @@ takeJ _ Empty = Empty
 takeJ n v@(Single _ _) | n == 0 = v
                        | otherwise = Empty
 takeJ n v@(Append t l r) | n > getSize (size t) = v
-                         | n < getSize (size (tag l)) = takeJ n l
-                         | otherwise = let rt = takeJ (n - getSize (size (tag l))) r in
+                         | n < leftSize = takeJ n l
+                         | otherwise = let rt = takeJ (n - leftSize) r in
                                        Append ((tag l) `mappend` (tag rt)) l rt
+                         where leftSize = getSize . size . tag $ l
+
+
+-- exercise 3 (Scrabble.hs)
+scoreLine :: String -> JoinList Score String
+scoreLine l = let scores = map scoreString . words $ l
+                  scoresAndWords = zip scores (words l)
+              in
+                foldr (+++) Empty $ map (\(s, w) -> Single s w) scoresAndWords
+
+-- exercise 4
+-- instance (Monoid a, Monoid b) => Monoid (a,b) where
+--   mempty = (mempty, mempty)
+--   (a,b) `mappend` (c,d) = ((a `mappend` c), (b `mappend` d))
+
+
+instance Buffer (JoinList (Score, Size) String) where
+  toString = unlines . jlToList
+
+  fromString = foldr (+++) Empty . map (\x -> Single (scoreString x, Size 1) x) . lines 
+  line n b = indexJ n b
+  replaceLine n l b = let pre = takeJ (n - 1) b
+                          post = dropJ n b
+                          (Append m1 _ _) = scoreLine l
+                      in
+                       pre +++ (Single (m1, Size (length l)) l) +++ post
+  numLines = \x -> case x of
+                     Empty -> 0
+                     Single _ _ -> 1
+                     Append _ l r -> numLines l + numLines r
+
+  value = \x -> case x of
+                  Empty -> 0
+                  Single (_, m2) _ -> getSize . size $ m2
+                  Append (_, m2) _ _ -> getSize . size $ m2
 
+main = runEditor editor $ Single (Score 244,Size 177) "This buffer is for notes you don't want to save, and for evaluation of steam valve coefficients. To load a different file, type the character L followed by the name of the file."
+--         [ "This buffer is for notes you don't want to save, and for"
+--         , "evaluation of steam valve coefficients."
+--         , "To load a different file, type the character L followed"
+--         , "by the name of the file."
+--         ]
+-- "This buffer is for notes you don't want to save, and for evaluation of steam valve -- coefficients. To load a different file, type the character L followed by the name of the file."