hw1: impl add, subtract, eq

hw1/BigNum.hs

@@ -28,7 +28,14 @@ bigAdd :: BigNum -> BigNum -> BigNum
 bigAdd x y = bigAdd' x y 0
 
 bigAdd' :: BigNum -> BigNum -> Block -> BigNum
-bigAdd' _ _ _ = error "Your code here"
+bigAdd' [] [] 0 = []
+bigAdd' [] [] c = [c]
+bigAdd' (x:xs) (y:ys) c = let s = x + y + c
+                          in (s `mod` maxblock) : bigAdd' xs ys (s `div` maxblock)
+bigAdd' (x:xs) [] c = let s = x + c
+                          in (s `mod` maxblock) : bigAdd' xs [] (s `div` maxblock)
+bigAdd' [] (y:ys) c = let s = y + c
+                          in (s `mod` maxblock) : bigAdd' [] ys (s `div` maxblock)
 
 bigSubtract :: BigNum -> BigNum -> BigNum
 bigSubtract x y =
@@ -44,10 +51,19 @@ stripLeadingZeroes xs = xs
 
 -- Negative numbers are not supported, so you may throw an error in these cases
 bigSubtract' :: BigNum -> BigNum -> Block -> BigNum
-bigSubtract' _ _ _ = error "Your code here"
+bigSubtract' [] [] 0 = []
+bigSubtract' [] _ _ = error "Negative numbers not supported"
+bigSubtract' (x:xs) (y:ys) b = let d = x - y - b
+                               in if d < 0
+                                  then (d + maxblock) : bigSubtract' xs ys 1
+                                  else d : bigSubtract' xs ys 0
+bigSubtract' (x:xs) [] b = let d = x - b
+                               in if d < 0
+                                  then (d + maxblock) : bigSubtract' xs [] 1
+                                  else d : bigSubtract' xs [] 0
 
 bigEq :: BigNum -> BigNum -> Bool
-bigEq _ _ = error "Your code here"
+bigEq x y = stripLeadingZeroes x == stripLeadingZeroes y
 
 bigDec :: BigNum -> BigNum
 bigDec x = bigSubtract x [1]

hw1/output

@@ -0,0 +1,13 @@
+Addition
+[455,1]
+[455,3]
+[455,235,681]
+[455,235,681]
+[455,1,681]
+Subtraction
+[999]
+[962,634,9]
+[1]
+[0]
+Multiplication
+7