haskell: Remove some redundant parenthesis.

Actually this changes the semantics of the program slightly: Node becomes
a (curried) 3-ary constructor rather than a unary constructor accepting
a tuple.  This is all to the good.

diff --git a/haskell-fringe.hs b/haskell-fringe.hs
index 78c6362..4ca9a3e 100644 (file)
--- a/haskell-fringe.hs
+++ b/haskell-fringe.hs
@@ -58,12 +58,12 @@ eof = do
 -----------------------------------------------------------------------------
 -- Tree data type.
 
 -----------------------------------------------------------------------------
 -- Tree data type.
 

-data Tree a = Leaf | Node (Tree a, a, Tree a) deriving (Show)
+data Tree a = Leaf | Node (Tree a) a (Tree a) deriving (Show)

 
 -- Return the elements inorder, as a list.
 fringe t = gather t [] where
   gather Leaf ns = ns
 
 -- Return the elements inorder, as a list.
 fringe t = gather t [] where
   gather Leaf ns = ns

-  gather (Node (l, x, r)) ns = gather l (x : gather r ns)
+  gather (Node l x r) ns = gather l (x : gather r ns)

 
 -- Answer whether two trees have the same fringe.
 sameFringe t tt = fringe t == fringe tt -- trivial!
 
 -- Answer whether two trees have the same fringe.
 sameFringe t tt = fringe t == fringe tt -- trivial!


@@ -81,7 +81,7 @@ parseTree cs = parse cs $ do t <- tree; eof; return t
     case r of
       Just '(' -> do
         step; left <- tree; c <- anytok "no data"; right <- tree; delim ')'
     case r of
       Just '(' -> do
         step; left <- tree; c <- anytok "no data"; right <- tree; delim ')'

-        return $ Node (left, c, right)
+        return $ Node left c right

       _ -> return Leaf
 
 -----------------------------------------------------------------------------
       _ -> return Leaf
 
 -----------------------------------------------------------------------------