diff --git a/day8.hs b/day8.hs
new file mode 100644
index 0000000..1ebaea6
--- /dev/null
+++ b/day8.hs
@@ -0,0 +1,114 @@
+{-# LANGUAGE FlexibleContexts #-}
+
+import qualified Data.Vector as V
+import Text.Parsec
+
+data Op = Acc Int
+        | Jmp Int
+        | Nop Int
+        deriving Show
+
+main :: IO ()
+main = do
+  raw <- readFile "day8.txt"
+  let ops = V.fromList $ zip (repeat False)
+              $ validate $ map (parse lineP []) $ lines raw
+      ansA = solveA ops
+      ansB = solveB ops
+   in do
+     putStrLn $ "day7a: " ++ (show ansA)
+     putStrLn $ "day7b: " ++ (show ansB)
+
+solveA :: V.Vector (Bool, Op) -> Int
+solveA ops = runMachineA ops 0 0
+
+solveB :: V.Vector (Bool, Op) -> Int
+solveB ops = case testSwaps ops 0 of
+               Nothing -> error "unsolvable?"
+               Just x -> x
+
+runMachineA :: V.Vector (Bool, Op) -> Int -> Int -> Int
+runMachineA ops pc ac = do
+  let (check,op) = ops V.! pc
+   in case check of
+    True -> ac
+    _ -> do
+      let nac = case op of
+                  (Acc x) -> ac + x
+                  _ -> ac
+          npc = case op of
+                  (Jmp y) -> pc + y
+                  _ -> succ pc
+          nops = ops V.// [(pc, (True, op))]
+        in runMachineA nops npc nac
+
+swapOp :: V.Vector (Bool, Op) -> Int -> Maybe (V.Vector (Bool, Op))
+swapOp ops ind =
+  case op of
+    (Acc _) -> Nothing
+    (Nop x) -> Just $ ops V.// [(ind, (check, Jmp x))]
+    (Jmp x) -> Just $ ops V.// [(ind, (check, Nop x))]
+  where
+    (check,op) = ops V.! ind
+
+testSwaps :: V.Vector (Bool, Op) -> Int -> Maybe Int
+testSwaps ops ind
+  | ind >= V.length ops = Nothing
+  | otherwise =
+    case res of
+      Nothing -> testSwaps ops $ succ ind
+      (Just nops) -> case (runMachineB nops 0 0) of
+                       Nothing -> testSwaps ops $ succ ind
+                       x -> x
+
+  where
+    res = swapOp ops ind
+
+runMachineB :: V.Vector (Bool, Op) -> Int -> Int -> Maybe Int
+runMachineB ops pc ac =
+  if pc == V.length ops
+  then Just ac
+  else do
+  let (check,op) = ops V.! pc
+   in case check of
+    True -> Nothing
+    _ -> do
+      let nac = case op of
+                  (Acc x) -> ac + x
+                  _ -> ac
+          npc = case op of
+                  (Jmp y) -> pc + y
+                  _ -> succ pc
+          nops = ops V.// [(pc, (True, op))]
+        in runMachineB nops npc nac
+
+validate :: [Either ParseError Op] -> [Op]
+validate [] = []
+validate ((Left _):_) = error "invalid input"
+validate ((Right b):bs) = b:(validate bs)
+
+lineP :: Parsec String () Op
+lineP = do
+  o <- opP
+  whitespaces
+  i <- intP
+  whitespaces
+  eof
+  return $ o i
+
+intP :: Parsec String () Int
+intP = do
+  s <- oneOf ['+','-']
+  v <- many1 digit
+  return $ (if s == '-' then -1 else 1) * (read v)
+
+opP :: Parsec String () (Int -> Op)
+opP = do
+  o <- (string "acc") <|> (string "jmp") <|> (string "nop")
+  case o of
+    "acc" -> return Acc
+    "jmp" -> return Jmp
+    _ -> return Nop
+
+whitespaces :: Parsec String () String
+whitespaces = many $ char ' '
diff --git a/day8.txt b/day8.txt
new file mode 100644
index 0000000..5ef799e
--- /dev/null
+++ b/day8.txt
@@ -0,0 +1,626 @@
+acc +48
+nop +308
+acc +33
+acc +48
+jmp +379
+acc +27
+acc +23
+acc +29
+acc +3
+jmp +326
+acc -12
+nop +248
+nop +146
+jmp +293
+acc +8
+acc -16
+acc +18
+jmp +255
+jmp +390
+jmp +442
+acc +38
+jmp +451
+jmp +499
+acc +41
+acc +44
+nop +298
+acc +31
+jmp +337
+acc -3
+acc +34
+nop +266
+acc -19
+jmp +281
+jmp +232
+acc -9
+acc +25
+acc -8
+nop +228
+jmp +79
+jmp +58
+acc +38
+nop +318
+jmp +17
+acc +44
+jmp +298
+acc -4
+jmp +196
+jmp +249
+acc -9
+acc -3
+acc +17
+jmp +556
+jmp +1
+acc -15
+jmp +166
+acc +23
+acc +10
+acc +39
+jmp +475
+acc +28
+jmp +41
+jmp +322
+acc +48
+acc -11
+acc -13
+acc +12
+jmp +92
+jmp +1
+acc +9
+jmp -26
+acc +4
+acc -8
+nop +484
+acc -14
+jmp +526
+acc -13
+acc -2
+acc -13
+jmp +419
+acc +22
+acc -17
+jmp +1
+jmp +151
+acc +3
+acc +2
+acc -13
+acc -11
+jmp +352
+acc +24
+jmp -27
+nop +206
+acc +22
+nop +225
+jmp +360
+acc +48
+jmp +105
+jmp +80
+acc -16
+jmp +89
+acc +0
+jmp +339
+acc +37
+acc +41
+nop +156
+jmp +452
+jmp +208
+nop +60
+jmp +155
+acc -16
+jmp +274
+nop -77
+acc -16
+acc +21
+jmp +508
+acc -7
+acc -1
+jmp -83
+acc -11
+jmp +28
+acc +3
+acc +32
+acc -18
+jmp -89
+acc +4
+acc -14
+acc -1
+acc +33
+jmp -75
+nop +185
+acc +8
+acc +22
+acc +26
+jmp +164
+acc -19
+jmp +260
+jmp +174
+acc +2
+acc +34
+jmp -120
+acc -15
+acc +48
+jmp +165
+acc +5
+nop +240
+jmp -121
+jmp +114
+jmp -36
+nop +432
+jmp +1
+acc -18
+jmp +429
+acc +44
+nop +110
+jmp +198
+acc -18
+acc +32
+acc +41
+jmp +102
+nop +177
+acc +35
+acc +24
+acc +46
+jmp +121
+acc +20
+jmp +1
+jmp +407
+jmp +1
+acc +35
+acc +46
+nop -18
+jmp +6
+jmp +422
+acc -19
+jmp -85
+acc +33
+jmp -116
+nop +79
+jmp +284
+acc +3
+acc +49
+nop +317
+jmp +6
+acc +6
+jmp +295
+nop -141
+acc -4
+jmp -44
+nop +155
+acc +48
+acc -17
+jmp +188
+acc +22
+jmp +286
+nop +103
+acc -2
+acc +45
+jmp +20
+acc +21
+acc +37
+jmp +235
+jmp +42
+acc -11
+nop -15
+acc -5
+jmp +235
+jmp +178
+acc +12
+acc -15
+jmp +25
+acc +9
+acc +11
+nop +389
+acc +50
+jmp +146
+acc +26
+jmp +144
+acc -14
+jmp +304
+nop +254
+jmp +337
+jmp +17
+jmp +1
+acc +6
+acc -4
+acc +42
+jmp +117
+acc +25
+acc +50
+acc +45
+jmp -112
+acc +14
+acc +27
+jmp +347
+nop +15
+jmp +14
+acc +29
+jmp +236
+jmp -71
+acc -11
+acc +21
+nop +32
+jmp -162
+acc -15
+jmp +322
+acc -4
+acc +16
+jmp +1
+jmp +100
+jmp +1
+jmp -77
+acc +21
+nop -199
+acc +49
+acc -1
+jmp -231
+jmp +230
+acc -19
+jmp +1
+jmp -49
+jmp -11
+acc +6
+jmp -110
+jmp +331
+acc +44
+jmp +292
+acc -7
+acc -18
+acc +50
+jmp +221
+acc +33
+acc +7
+jmp -45
+jmp +342
+acc -19
+acc +36
+acc +15
+jmp -229
+nop -5
+jmp +57
+acc +26
+acc +43
+nop -175
+jmp +82
+acc +45
+jmp -161
+acc -16
+acc +35
+acc +46
+acc +43
+jmp +1
+nop +195
+acc +39
+acc +27
+acc +32
+jmp +227
+jmp -272
+nop +201
+acc +6
+acc +13
+acc +12
+jmp -177
+acc -9
+acc +46
+nop +199
+acc -1
+jmp +1
+jmp +3
+acc +42
+jmp +75
+jmp +305
+acc +49
+acc -16
+jmp -92
+acc +3
+nop +279
+jmp +54
+jmp +31
+acc +50
+jmp -125
+acc +21
+nop -178
+acc +40
+jmp +193
+acc +39
+acc -5
+jmp +261
+nop -3
+acc -13
+jmp -310
+acc +6
+acc -17
+acc +12
+acc +38
+jmp +267
+jmp -311
+acc -2
+jmp -7
+nop +77
+acc -2
+acc +39
+acc -16
+jmp +10
+nop +59
+jmp -296
+acc -4
+acc +41
+jmp -249
+acc +43
+nop +35
+jmp +95
+jmp +171
+acc +10
+nop +169
+acc -17
+jmp +47
+acc +49
+acc +38
+nop +199
+jmp +249
+jmp -53
+nop -194
+acc +19
+acc +18
+jmp -16
+acc +33
+jmp +194
+nop -194
+acc +49
+jmp +85
+acc +50
+nop -318
+acc -7
+jmp -49
+acc -6
+acc +48
+acc -13
+acc -14
+jmp +67
+acc +12
+acc +19
+acc +3
+jmp -371
+jmp -149
+acc +49
+nop -202
+jmp -315
+acc -6
+jmp -171
+acc -7
+jmp +113
+acc +34
+acc +36
+acc +17
+jmp -97
+acc +3
+jmp -244
+acc +25
+acc +30
+acc +25
+acc -19
+jmp +44
+nop +84
+jmp +124
+nop +17
+acc -11
+acc -8
+acc +4
+jmp +193
+jmp -388
+acc +36
+acc +17
+jmp +1
+acc -5
+jmp +166
+acc +39
+acc -10
+jmp -280
+acc +15
+jmp +1
+jmp -396
+jmp +113
+acc +37
+acc +13
+jmp -35
+nop +109
+acc +8
+acc +6
+acc +19
+jmp +39
+jmp +1
+jmp +1
+acc +39
+acc -14
+jmp -291
+acc +39
+acc +31
+jmp -231
+acc +41
+jmp -55
+nop -167
+jmp +105
+acc -8
+acc +34
+jmp -114
+nop +58
+jmp +1
+nop -270
+acc +31
+jmp -135
+acc +8
+acc +33
+jmp +1
+jmp -64
+acc +24
+acc +16
+jmp +117
+acc +35
+acc -11
+nop +44
+acc +18
+jmp +1
+jmp +88
+acc +29
+nop +34
+jmp +1
+nop -118
+jmp -404
+jmp -144
+acc -12
+nop -372
+acc -14
+jmp -209
+acc +12
+jmp +1
+acc -1
+jmp +132
+nop -93
+jmp -130
+acc +23
+acc +30
+acc +3
+jmp -209
+nop -381
+acc -19
+jmp +23
+nop +87
+jmp -277
+acc +39
+jmp -391
+acc +14
+acc +18
+acc +24
+nop -459
+jmp -267
+acc +35
+nop +84
+jmp -231
+acc +5
+acc +0
+acc +45
+jmp -210
+jmp -211
+acc +7
+acc +8
+nop -249
+jmp -8
+jmp -105
+nop -455
+acc -19
+acc +36
+jmp -368
+acc +33
+acc +10
+acc +9
+jmp -259
+nop +41
+acc -14
+acc +2
+jmp -336
+acc +46
+jmp -261
+nop -284
+acc +21
+nop -154
+jmp -485
+jmp -505
+acc +32
+nop -327
+acc +1
+nop +43
+jmp -23
+acc -7
+jmp -88
+acc +10
+jmp -440
+acc +12
+jmp -430
+jmp +1
+acc +46
+nop -105
+jmp -87
+acc +49
+acc -10
+acc -6
+jmp -411
+jmp -268
+acc +35
+acc +15
+jmp +45
+acc -14
+acc +0
+jmp -234
+nop -67
+acc +32
+acc +1
+jmp -476
+jmp -297
+nop -274
+jmp -435
+acc +36
+acc -2
+acc +33
+acc +9
+jmp -26
+jmp +50
+acc +23
+jmp -172
+jmp +1
+acc +34
+acc +32
+acc -4
+jmp -312
+acc -11
+acc +26
+jmp -150
+acc +41
+nop -79
+acc +25
+jmp -76
+acc -2
+acc +29
+acc +12
+jmp -549
+nop -357
+nop -438
+jmp -320
+acc +7
+acc -6
+jmp -149
+nop -74
+acc +7
+acc +45
+jmp -383
+acc -8
+acc +5
+acc +12
+jmp -463
+acc -17
+acc +5
+jmp -34
+jmp +1
+acc +18
+jmp -523
+acc +38
+acc +35
+nop -222
+jmp -424
+nop -365
+jmp -188
+acc +0
+acc +7
+nop -167
+acc +27
+jmp -351
+acc +26
+jmp -201
+nop -208
+nop -466
+acc +50
+nop -531
+jmp -273
+acc +21
+acc +25
+nop -397
+acc +29
+jmp +1
diff --git a/flake.lock b/flake.lock
new file mode 100644
index 0000000..8eea272
--- /dev/null
+++ b/flake.lock
@@ -0,0 +1,43 @@
+{
+  "nodes": {
+    "flake-utils": {
+      "locked": {
+        "lastModified": 1605370193,
+        "narHash": "sha256-YyMTf3URDL/otKdKgtoMChu4vfVL3vCMkRqpGifhUn0=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "5021eac20303a61fafe17224c087f5519baed54d",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1607348767,
+        "narHash": "sha256-3ci3OKIQnYHDoeyCWJbV/H3sScLJewhWeW5qjLHENLQ=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "3a02dc9edb283beb9580c9329f242ad705a721c3",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-20.09",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}
diff --git a/flake.nix b/flake.nix
new file mode 100644
index 0000000..e253784
--- /dev/null
+++ b/flake.nix
@@ -0,0 +1,17 @@
+{
+  description = "ghc with plugins for aoc";
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-20.09";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+  outputs = { self, nixpkgs, flake-utils, ... }:
+    flake-utils.lib.eachDefaultSystem
+      (system:
+        let pkgs = nixpkgs.legacyPackages.${system}; in
+        {
+          defaultPackage = pkgs.haskellPackages.ghcWithPackages
+            (hpkgs: with hpkgs; [
+              vector
+            ]);
+        });
+}