Stopped makeEquations unnecessarily producing duplicate equations

common/Utils.hs

@@ -205,10 +205,18 @@ product2 (l0,l1) = [(x0,x1) | x0 <- l0, x1 <- l1]
 product3 :: ([a],[b],[c]) -> [(a,b,c)]
 product3 (l0,l1,l2) = [(x0,x1,x2) | x0 <- l0, x1 <- l1, x2 <- l2]
 
--- | Given a triple of lists, produces a list of pairs that is the cartesian product of the three lists.
+-- | Given a quadruple of lists, produces a list of pairs that is the cartesian product of the four lists.
 product4 :: ([a],[b],[c],[d]) -> [(a,b,c,d)]
 product4 (l0,l1,l2,l3) = [(x0,x1,x2,x3) | x0 <- l0, x1 <- l1, x2 <- l2, x3 <- l3]
 
+-- | Given a list, produces all possible distinct pairings of the elements.
+-- That is, for each pair returned, (A,B), B will not be the same element as A, and the pair (B,A) 
+-- will not be in the list.  Note that this is not the same as B /= A; if the source list contains
+-- two equal items, the returned pairs will feature a pair such that B /= A.
+allPairs :: [a] -> [(a,a)]
+allPairs [] = []
+allPairs (x:xs) = map (\y -> (x,y)) xs ++ allPairs xs
+
 -- | On the basis of a boolean check function, transforms x into Just x if the function returns True;
 -- otherwise Nothing is returned.
 boolToMaybe :: (a -> Bool) -> a -> Maybe a

transformations/ArrayUsageCheck.hs

@@ -134,7 +134,7 @@ makeEquations es high = makeEquations' >>* (\(s,v,lh) -> (s,squareEquations (pai
 
     -- Pairs all possible combinations
     pairEqs :: [(Integer,EqualityConstraintEquation)] -> [EqualityConstraintEquation]
-    pairEqs = filter (any (/= 0) . elems) . map (uncurry pairEqs') . product2 . mkPair
+    pairEqs = filter (any (/= 0) . elems) . map (uncurry pairEqs') . allPairs
       where
         pairEqs' (nx,ex) (ny,ey) = arrayZipWith' 0 (-) (amap (* ny) ex) (amap (* nx) ey)
     

transformations/ArrayUsageCheckTest.hs

@@ -232,26 +232,22 @@ testIndexes = TestList
    
    
    ,TestCase $ assertEquivalentProblems "testIndexes makeEq"
-     (Map.empty,(uncurry makeConsistent) (dupeEq [con 0 === con 1],leq [con 0,con 0,con 7] &&& leq [con 0,con 1,con 7]))
+     (Map.empty,(uncurry makeConsistent) ([con 0 === con 1],leq [con 0,con 0,con 7] &&& leq [con 0,con 1,con 7]))
      =<< (checkRight $ makeEquations [intLiteral 0, intLiteral 1] (intLiteral 7))
      
    ,TestCase $ assertEquivalentProblems "testIndexes makeEq 3"
-     (Map.singleton "i" 1,(uncurry makeConsistent) (dupeEq [i === con 3],leq [con 0,con 3,con 7] &&& leq [con 0,i,con 7]))
+     (Map.singleton "i" 1,(uncurry makeConsistent) ([i === con 3],leq [con 0,con 3,con 7] &&& leq [con 0,i,con 7]))
      =<< (checkRight $ makeEquations [exprVariable "i",intLiteral 3] (intLiteral 7))
      
    ,TestCase $ assertEquivalentProblems "testIndexes makeEq 4"
-     (Map.fromList [("i",1),("j",2)],(uncurry makeConsistent) (dupeEq [i === j],leq [con 0,i,con 7] &&& leq [con 0,j,con 7]))
+     (Map.fromList [("i",1),("j",2)],(uncurry makeConsistent) ([i === j],leq [con 0,i,con 7] &&& leq [con 0,j,con 7]))
      =<< (checkRight $ makeEquations [exprVariable "i",exprVariable "j"] (intLiteral 7))     
 
    ,TestCase $ assertEquivalentProblems "testIndexes makeEq 5"
-     (Map.fromList [("i",2),("j",1)],(uncurry makeConsistent) (dupeEq [i === j],leq [con 0,i,con 7] &&& leq [con 0,j,con 7]))
+     (Map.fromList [("i",2),("j",1)],(uncurry makeConsistent) ([i === j],leq [con 0,i,con 7] &&& leq [con 0,j,con 7]))
      =<< (checkRight $ makeEquations [exprVariable "i",exprVariable "j"] (intLiteral 7))
   ]
   where
-    -- Duplicates each equation by adding its negation to the list
-    dupeEq :: [HandyEq] -> [HandyEq]
-    dupeEq = concatMap (\(Eq e) -> [Eq e,Eq $ negateVars e])
-    
     -- Given some indexes using "i", this function checks whether these can
     -- ever overlap within the bounds given, and matches this against
     -- the expected value; True for safe, False for unsafe.