Complete part 1 of day 2 puzzle

2/navigator.hs

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+main :: IO ()
+main = do
+  instructions <- getContents
+  let
+    parsed = parseInstructions instructions
+    location = navigate parsed
+    solution1 = uncurry (*) location
+  print solution1
+
+parseInstructions :: String -> [(Int, Int)]
+parseInstructions instructions =
+  map parseLine (lines instructions)
+  where
+    parseLine line = case break (== ' ') line of
+      ("forward", distance) -> (read distance, 0)
+      ("down", distance)    -> (0, read distance)
+      ("up", distance)      -> (0, (-read distance))
+      _                     -> error "Invalid line"
+
+navigate :: [(Int, Int)] -> (Int, Int)
+navigate instructions =
+  foldl1 sumTuples instructions
+  where
+    sumTuples :: (Int, Int) -> (Int, Int) -> (Int, Int)
+    sumTuples (a, b) (c, d) = (a + c, b + d)

2/sampleinstructions.txt

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+forward 5
+down 5
+forward 8
+up 3
+down 8
+forward 2