1 files changed, 34 insertions, 0 deletions
diff --git a/2020/08a.hs b/2020/08a.hs
new file mode 100644
index 0000000..846c3df
--- /dev/null
+++ b/2020/08a.hs
@@ -0,0 +1,34 @@
+module Day8A where
+
+import System.Environment (getArgs)
+
+data Instruction = Nop | Acc Int | Jmp Int
+    deriving (Eq, Show, Ord)
+
+readSigned :: String -> Int
+readSigned ('+':xs) = read xs
+readSigned xs = read xs
+
+parseInstruction :: String -> Instruction
+parseInstruction xs | ins == "nop" = Nop
+                    | ins == "acc" = Acc num
+                    | ins == "jmp" = Jmp num
+                         where ins = take 3 xs
+                               num = readSigned $ drop 4 xs
+
+execUntilLoop :: [Instruction] -> [Int] -> Int -> Int -> Int
+execUntilLoop is vs ip ax | ip `elem` vs = ax
+                          | otherwise = case ins of Nop -> execUntilLoop is vs' (ip + 1) ax
+                                                    Acc x -> execUntilLoop is vs' (ip + 1) (ax + x)
+                                                    Jmp x -> execUntilLoop is vs' (ip + x) ax
+                            where ins = is!!ip
+                                  vs' = ip : vs
+
+main :: IO ()
+main = do 
+        args <- getArgs;
+        content <- readFile $ head args;
+        let l = lines content;
+        let is = map parseInstruction l;
+        print $ execUntilLoop is [] 0 0;
+        return ();
+\ No newline at end of file