From 4ffd27205da45892c8dae576eea71ccfb46bf85a Mon Sep 17 00:00:00 2001
From: Riley Apeldoorn <me@riley.lgbt>
Date: Fri, 10 Dec 2021 09:43:35 +0100
Subject: [PATCH] Day 10 ez pz

---
 10/example.txt |  10 +++++
 10/input.txt   | 106 +++++++++++++++++++++++++++++++++++++++++++++++++
 10/solution.hs |  60 ++++++++++++++++++++++++++++
 3 files changed, 176 insertions(+)
 create mode 100644 10/example.txt
 create mode 100644 10/input.txt
 create mode 100644 10/solution.hs

diff --git a/10/example.txt b/10/example.txt
new file mode 100644
index 0000000..b1518d9
--- /dev/null
+++ b/10/example.txt
@@ -0,0 +1,10 @@
+[({(<(())[]>[[{[]{<()<>>
+[(()[<>])]({[<{<<[]>>(
+{([(<{}[<>[]}>{[]{[(<()>
+(((({<>}<{<{<>}{[]{[]{}
+[[<[([]))<([[{}[[()]]]
+[{[{({}]{}}([{[{{{}}([]
+{<[[]]>}<{[{[{[]{()[[[]
+[<(<(<(<{}))><([]([]()
+<{([([[(<>()){}]>(<<{{
+<{([{{}}[<[[[<>{}]]]>[]]
diff --git a/10/input.txt b/10/input.txt
new file mode 100644
index 0000000..0c95ec7
--- /dev/null
+++ b/10/input.txt
@@ -0,0 +1,106 @@
+<{({(([[<<([[([][])]{([]<>)([]<>)}]<[[[]{}]{()[]}]>)(<<[[]()][[]()]><[<>[]]<[]()>>>{<<<><>><<>[]>>[<[]<>><
+{<[<((<<({([{{{}[]}<<><>>}]<<{[]<>}([]<>)>>)<{(<[]()>{()()})<(()<>){(){}}>}([(()[])<[]>][[[][]]{{}}])
+<{[[{<[[{(<[[({}())[()()]]([<>()](<>()))][(([]<>)([][]))(({}{})[<><>])]><<<[[]<>][{}[]]>([<>{}
+<[[<[([({[{<[({}<>)([]<>)](<<>[]>([]()))><[<[]{}>[<><>]]>}>[{[[({}<>)<()<>>][{{}[]}(()())]][[(<>{}){<>{
+[((<{((([[<<<[<><>]{{}[]}>>(([<><>]<()[]>)<(()<>)>)>([[[{}{}][[][]>]<{<>()}[<>{}]>])]]<{[<[
+([{([[[{(<({<<[]<>>[()()]>{(()[])}})<(<<{}()>(<>>>([(){}]))<[(<>{}){()}]((()[]){()()})>>>)}{
+<{{[(<[<<[[{<(()[])>[[{}()]{{}[]}]}[[(<>())[()()]]{<{}{}>}]](<{[<><>]{{}{}}}<({}[])[<><>]>><{[{}<>](<><>)
+{({<[<([[(({({<>()}{{}{}})})<<<((){})[[]()]><{{}()}[[][]]>>{(<{}{}>{{}()})}>)<<{<[{}[]][{}{}]>([[][]]{
+{[(((((<{[({<{()[]}(()())>{<(){}>{{}()}}}(<[<>()]{[]()}>(<()()>{{}<>})))[<[[{}{}](<>()>]({[]<>
+(([((<{<[((<{{<><>}{[]{}}}><<<<>>[{}]>([[]{}]<<>[]>)>)[[{<{}>{()()}}[[{}[]](()()>]](<<<>{}>[[]
+{<([[{<{([[<([[]<>]({}{})){{{}()}({}[])}>](<(<()()><()[]>)<<[]<>>([]{})>>)]){[{<<[()[]]<<>{}>><({
+<{[[([<<<(<{{(()<>)(()())}([{}<>]((){}))}>)>({({{{()<>}({}<>)}<[[]<>]{<>[]}>})(({<(){}>[<>[]]}<([]{})<[]{}>>)
+(<{<{[[({(<[((<>[]){{}})<(<><>)<[]{}>>]((<<>[]><[]()>)<<{}{}>{(){}}>)>(<[[[]<>]]{{<>{}}{[]()}}>(<{
+{(({{[[{<[((<<()<>>[{}{}]>((()<>){[]()})){{(<>{})[<>[]]}<<<><>>>}){{({<>{}}([]()))[{<><>}{[]
+(([<(([({{<{[{()<>}<{}[]>]}{[[()()][()<>]}[{<>{}}({}{})]}>((<<<>{}>[<>()]>{{[]<>}({}{})}){[<{
+[[{{(<<[[[[<<<<>{}>({}())>[([]<>)(()())]>]<<<{<>()}>[<<>[]>[()()]]>[([[]()]<[][]))<[<>{}]{{}<>
+{[{(((([<[{([(()()){()()}][<(){}>[{}<>)])[(<{}<>>{<>()})({{}<>}[()[]])]}(<({[]<>}<()[]>)({[]<>
+<<([(([{<{<<<[{}[]]((){})>((<>[])(()<>))>{{{<>()}{[]}}{([][])}}>[<{{<>[]}<<>>}({[]<>})>]]({({{<><>
+[{((<{<[[<[{[{{}<>}]{[{}][<>[]]}}[<([]())<()[]>>((<>){[]{}})]]<{(<()<>><{}<>]){[[]<>]({}{})}}({<{}[]>{{}
+<[<{(<[[<(((<({}[])><(<><>)(<>())]){{{()()}(<>())}<[{}()]>})[([[<>[]]{{}[]}]{{{}()}<{}[]>})[[(()<>){<>
+[([{{[<([{[([[()<>]])([[<>][()[]]][[<>[]]<<>[]>])]}{([<<{}()>({})>(<[]()>(<><>))]<<{{}<>}{<>}><(<>
+<<[[([([(<(<<[{}[]]<()[]]><{[]{}}[<>()]>>)>[<<({[][]}<<><>>)[<{}{}>{()<>}]><({<>{}}([]))((
+<({<{(<[({([[{()}(<><>)](<[][]>[{}{}])](([[]<>]<<>{}>))){({<<>{}>[[]{}]}<([][])>)<<(<><>)<[]<>>}>}}((([[()<
+{([<(<[(({[({[(){}]<<>{}>}[[{}{}][{}[]]])]{({[()<>]{()[]}}(<[][]>[()[]])){{{[]{}}(<>[])}[<(){}>(
+<[<[<{[{<[{[<<{}<>>(<>)>]{<({}{}){(){}}>((<>{})[{}<>])}}[<[[<><>]{{}<>}]{<()()>}>{<<[]()>(()())>{{{}<
+(({[[<<[({[{{<()()>}}{<[<>()]>}][(<{[][]}>{[{}()]{[]<>}})<{{<>{}}(()[])}{{[]()}<<>[]>}>]})
+<((<([[({(<{[[(){}]<[][]>]}>({<[()<>](()[])>(([]<>)([]<>))}<{[[]<>]{(){}}}(<()<>>([][]])>))}<{[<[({}
+{({{{[[{{[{(<<(){}>[{}{}]>((()<>)[<>{}]))[<<{}[]><[]>>[{{}{}}(<>[])]]}[(<<(){}>({}{}))((<>{})([]<>)))
+[[(({[{(<({[{<[]()>{()[]}}<(<>())<()()>>]<(({}[]){{}<>])((()<>){{}[]})>}([[({}{})[<>()]][{<><>}]]{([[
+[[{<[([<[((<([[]{}][{}<>])([{}<>])>[([()<>]{{}{}}){{[]()}}])<({{[]()}[[]()]))>)([<<<<>{}><{}()>><(<>
+<<({{{<{[<{<{<[]<>>[[]{}]}[<[]()>{[]{}}]>[[[(){}][<><>]]{(<>[]}({}{})}]}><[[({{}[]}{[]()}){(<>())[()<
+{{(({[[[{<[<(([]())([]{}))([{}{}](()[])}>]>}([<{[[[]()][(){}]]<{<>[]}>}({<()<>><[]<>>})>((([()
+(<(({{(([(({{<{}[]>({}())}([<>[]][{}()])}((<[][]>{()<>}){[[]<>]<{}{}>}))<({{[]<>}([][])}{<[]{}>{<>[]}})
+((([<([([{{{<<<>{}><{}[]>>[[<>[]][{}[]]]}}(([<<>{}>[()[]]][{{}{}}])(<[()()][<><>]>{{<>[]}})}}]<{[[<
+{{(<[<[<[<<[[(<>[])]({<><>}[()()])]>>]>[{{[[{(<>[])([][])}{[[][]]([]())}]>[[[<{}{}>({}())]<{<>
+<[{[[([[{[(<[<{}{}>{(){}}][{[]<>}<()[]]]>(([()<>][[][]]){[<>{}](()[])}))[[<<{}>[<>{}]>[({}{})({}{})]]<([[]{}
+({<<<{<({{{{{[()()]({}())}[[[]{}][<><>])}({<()()><[]()>}({<>()}))}{(((<>()){()()}){<(){}><()[]>})(([{}()]
+([<({[{({(<<{[{}()]}{{{}[]}((){})}>>)<<{[((){})[()]]}<<{[]<>}<<>()>>([<>()][[]<>])>>{<<[<>[]]<[]<>>)<{<
+(<[<<(<[[[[{{({}<>)[{}{}]}<[[]{}]([]<>)>}][<[<<>{}>{[]}][[[]{}](<>())]><<[<>()][(){}]><{[]
+(({[[(([<(([{({}[])[<>{}]}{(<>[])({}{})})<<<{}[]>({}())>[({}<>)<{}()>]>)[<<[[][]]((){})><{{}(
+{[((<([<[{[{<[<><>][()()]><{<>{}}>}[{<[][]>[()<>]}<(<>())<()<>>>]]<<<(<>())<()[]>>>[{{{}[]}}[[{}()]((){
+{{<{({{({[<((({}{}){<>[]}){<{}()>{<>[]}})>(<{<<>{}><[]<>>}>[[{[]<>>{<><>}]{((){})<(){}>}])]}(<{[{{<><>}{[
+(({<[[{[(<(((({}{}){()<>}))<{{[]{}}{{}{}}}<[{}<>][(){}]>>)>[{{(<<><>>([]{}))[((){})<{}[]>]}}(([[<>()]{<>()}]
+[<([[[<[<{<{<{[]{}}{[]{}}>[([]())<<>[]>]}({{[]{}}<[]()>}<({}())(<>{})>)>}[({[[{}[]][{}<>]]})]>]><[
+<{[<<[[<{[[{<<{}[]>[<><>]>}({[[]{}]<{}()>}((()[])))]{[<{()}[[]{}]>]{(({}[])<{}()>)<(<>())[()<>]
+[[([[{[[(([{[[<>()]{<>()}]({(){}}({}{}))}[<[<><>]([]())>(<[]()><{}[]>)]]{(<<<><>>[[]{}]>(<[][]>((){}))
+{(<<[[{[{{(<<<{}[]>(<>[])>({[]{}}([]{}))>[{<<>()>[[]<>]]([{}[]])])}[[{(<<><>>[()()])<<<><>>>}([<<>
+([((<(<[(<{((<{}{}>{<><>})){{(()[])[{}[]]}}}{[[[(){}][<><>]]]({<()<>>{{}[]}}<[()()]{()[]}>)}>[<{(<{}
+[(<[([[({({<[{<>()}([]<>)][(<><>)<()[]>]>})[{([(())({}[])][{[]<>}<()<>>])}({<[{}{}](()())><({}())[<>[]
+([(<<[<{<{((<(<>[])({}<>)>{{()()}<<>{}>}))<{[[()[]][()[]]][({}[])<{}()>]}{<({})><{[][]}{{}<>}>}>}<<<({(){}}
+[(<{(([({<{{(<[]<>>({}()))}}[<[[{}[]][[]]]>[({[]<>}(<>{}))]]>})]<([(<([[()()][[][]]]<((){}
+((({([(<<{{<<({}())(())>([<>()]<()()>)>}}<[(<{{}[]}<()<>>><({}{}){(){}}>)][(({()<>}([]()))([()]))({{{}()}
+{<(({[<([{[({([][])[[]{}]}<({}<>)<<>()>>)<<{<>()}{[]<>}>{{{}}{[]()}}>]}])<<{<(([[]{}]<<>[]>)){<<[]<>>><<()[
+[{<(<<<((<<<{[()<>]{[]<>}}>[[<{}{}>[()[]]]<(<><>)[()[]]>]>{[[[[]()][<>[]]]]({(<>}{[]{}}})}>){({
+<<[((<<[{{[(<[<>()]><{{}[]}{<>{}}>){[(()[])([]())][[(){}][{}[]]]}]([<[[][]]{(){}}><<{}{}>{<>{}}>][[
+{<<{<<{<({[[([<>{}])[{[]<>}{{}[]}]][[<()<>>[<>{}]]]]<([{[]()}({}{})]({[]()}{<>()})){[({}<>)[[]{}
+{<<[{((([<([[<[]()><<><>>][{()<>}<[][]>]]{<[{}[]][()[]]>[{<>{}>{[]}]}){[([[]{}]<()[]>)[[<>()][{}[]]
+({{{{<([[((({{{}{}}<()[]>}{<()<>>{{}<>}})(<({}{})>({<>{}}[[]()]))){(<<<><>><()[]>>[{()()}{[]<>}
+({<{[[{({{[<[{[][]}<[][]>]{(<><>)}>([[<>{}][<>{}]]({[]{}}<<>[]>))]}{[({[[]]{()[]}}{(<>{})[()()]})(<{(
+[{<<<[(<(<{((([]{}))[{<>()}[()[]]]){{<{}{}>}[<[]<>>{<>{}}]}}<(<[<>[]][()()]>)<([{}()]{{}[]})
+{{(([[([((<([[<><>]])>({[{()<>}<[]{}>]}<{[()()]<{}>}(<{}<>>({}{}))>))[{{([()()]<{}<>>){(<>{})(
+([(<{[[{<{{<{([]())(<>[])}{{[]<>}{()<>}}>{{{()}}[<[]{}><{}<>>]}}<{[{()()}]{{<>[]}[<><>]}}<<{<>(
+([[{[{[{<<(<{<{}{}>{[]}}{[{}{}]{()[]}}>[{({}[])}<[()[]]>])>>[(<<({<>{}}{[]{}})>>(<[([]()){()<>}]((()())([]
+(({<({<([(({<<<>()>([]())>{<()[]>{[]<>}}}(<{{}<>}[()()]>({{}<>}[{}()]))))]){{<[{[(<>[]){()
+([[(<{[[{<[<(<[]()>[{}[]]){[<><>]{<>[]}}>{{([]()){[]{}}}<((){})([]<>)>}]<<<{{}[]}[()]>(<{}><[][]>)>>>}
+{{(<[{[([<<<[<{}<>>(<>{})]<({}[])[<>[]]>>({<{}{}><[]{}>}<<[]><(){}>>)>>(((({()()}[[]{}]))<[{[]<>)<[]()>]
+(({{<<[{([[({[[]{}]{()<>}}[(<><>)[()()]])[<[<>[]]><([]{})[[][]]>]](<((<><>)<<>()>)[([][])((){})]>[(
+((<<([[<{[{({<(){}><[][]>}{(()[])({}[])})({[{}()]({}{})}(<(){}>(<><>)))}{{[{()<>}<{}{}>][{[]{}}(()
+<{(((([<[((({{{}<>}[[]<>]}<[{}<>]>)[<({}{})>{{[]()}<{}()>}])<([<<>>(<><>)]((()())(<>{})))>){(({(
+<{{<<{{{[({{[<()[]>(()[])]}<<[[]<>][[]]>>}[<[({})<<>[]>][[[]]([][])]>])]}}(<({[[<[(){}]>{<[]{}>}]{(({
+[([[(({([{{({{()}[{}<>]}{({}<>){{}()}}]}}{[<<({}())<(){}>>[{()[]}([]{})]>]{<<{{}()}(<>[])>{[(
+[{[{[([<<((<<{()<>}<<>()>>[{[]{}}{{}[]}]>[[{[][]}{{}}]])(([((){})(()())]{[(){}]{()}})))}{(<<<<<><>>({}[]
+<[{({[({[({{(<[]()>{{}<>}){{{}<>}[(){}]}}(([{}()]<[][]>)[[<>]({}{})])}<<[(<>)({})]<<()[]><
+[((([<(({<<({{{}()}({}<>)}({()[]}[{}{}]))>{[{(<>[])}{(<>[])<{}[]>}]{<[<><>][()[]]>}}>({<{<<>()><<><>>}([{}[]]
+{({((<<([((<[[()[]]{[][]}]<{(){}}{<>{}}>>({[(){}][<>]})))(<(({<>[]}<(){}>)(<()[]><{}()>))>)]){
+<{<[<(<{<[({{{{}<>}<<>{}>}{[[]()][{}{}]}}[({<><>}{<>{}})[[{}()]{[]()}]])({{<[])(<>[])}})](<<[[<><>]](<{}{}>
+[([[[{[((<<(<<()()>>)><<{([]()){<>{}}}<{[]{}}<()()>>>[(<<><>>[()[]]){((){})([]{})}]>>({[<[<><>]{<><
+<{{({{{[<{[{{{()<>}[<><>]}[(()[]){[]{}}]}(<{{}[]}[<>[]]><{{}{}}<{}[]>>)]{(({(){}}<<>{}>)[<<><>>[{}
+[[([[{[({[{[({{}[]}{()[]})[<()()>{{}{}}]][(([]<>)<[][]>)[<{}{}><{}()>]]}][<([([][]){()()}][[{}{}]{()<
+{(<<(((<((((<{()<>}<<>[]>)[<[][]>[{}()]]){[[[]<>]<(){}>][<()<>>{{}<>}]})))<[{{[{{}{}}<[]<>>]}}(
+{[(<{[<{{({[{[<><>](<>{})}{({}[])(<>{})}]}({<({}[])<[]<>>>(({}[]))}[<<()><<>>}[{()[]}{[][]}]])){[({<<>()>(
+<([{[(<(<<([((()())<{}{}>)]<{(<>())(<>()]}{[()<>](<>())}>)<[[<[][]>]{{()}<<><>>}](({()()}[[
+<[<[<{{{[{((<(()()){{}<>)><[[]()](()<>)>))({[[<>{}]{{}()}]({()<>}(()[]))})}]}([{((({{}()}[()<
+[{([({[<(<{[{[<>[]][<>()]}([[]{}](()()))){{[()()]<(){}>}({()[]}<[]()>)}}<{[(<>[]){()<>}][[()<>]{()[]}]}{<(<>
+{((<(<({{([{[([]<>){[]<>}](<[]<>>[[]<>])}{{<[][]><()[]>}({()<>}<<>{}>)}]<[<[<>()]([]{})><{{}<>}<{}<>>>][(
+{<<([<(<{[[{{{<>[]}[[]<>]}{[{}[]]]}{<[(){}]>{[{}()]{[]<>}}}](<{[[]<>]{<>[]}}<<()<>>[[]()]>>)]<[{{<{}>[{}]}<(
+[[{{{<{[{({<<<[]{}>[()<>]><[[]<>]([]<>)>><{<<>()>[<>{}]}>}((<[{}{}]{[]}]{<[]<>>{<>{}}})[([<>(
+[[{<<{{[(([[[{()[]}][[()[]]<[]>]]({{{}}})][({([][])[{}{}]}<[(){}]<()[]>>){<{[]{}}[(){}]><{{}{}}<<>()>]}]))<<
+[(({[<<{<({<([<><>])[{<>()>{{}[]}]>((<()<>><{}<>>)[{[][]}([]{})])})<{{([[]<>]<{}<>>)([()[]]{()()}
+[([(({(<[<[<((<>{})[[]<>]){[<><>]({}[]>}>]>]>)}[(({(<<[{(){}}[()[]]]>[<(<>{}){{}{}}>[[()<>][()]]]>)
+{<{{<({<{((<{({})<<>{}>}((()){()<>})>))}((<{((()[]){{}[]})[<<>>[[]<>]]}(([<>](()<>)))><{{{<>()}((){}}}((
+<[<{<((({{[<{{[][]}}<([]<>)(<>{})>>]}[(([{()()}{<>()}])[<[()[]][()[]]>]){<<[<>()](<>{})>{{(){}}(<>
+(([{([{[<(<(((()<>))[(())(<>{})])([[{}<>]{{}[]}][{<><>}[{}{}]])>[(([()[]]<[][]>)[{{}[]}(()[])])(([{}{}]
+{<(<<{<[{<{<<<<>[]>[[]<>]){[[]()][<><>]}>({(<><>)(()<>)})}>[<([{{}{}}<[]<>>])({{[]<>}({}[])})>]}{<<[(
+<{([({{{<{[{(([]())<<><>>)<[()()]((){})>}]}(<{(<(){}>(<>()))}([[()[]][(){}]](<<>{}>[{}()])}>)>([{<(
+((([{<<[{{[(<<[]<>>(<>())>{({}{})<{}[]>})[[<()()>[<>[]]][<{}[]>(()())]]]}}]>>)]{{{{[[{[[[([]<>){
+({(<{{({[[{<<(()[])[()]>[{<><>}{<>[]}]>{<{<><>}{()[]}>{[{}()]{[][]}}}}{<<{[]<>}(<><>)>{{[]{}}[
+(<[{{(([<{{(<[<>()]((){})>{<{}[]>({}())})}}>][<[{{([{}[]])<([]<>)<<>{}>>}}{<({[][]}(()()))(<<>()>{
+(<<{{{((<{({<<{}()><{}{}>><<()[]>[<>[]]>>(<[(){}]([]<>)>[({}<>)]))(({{[]<>}<()<>>}[<()[]>(()[])]){<[
+<[(((<({([({{[[]()]{[]()}}([{}()]<[]<>>)}[[<()[]>{{}{}}]([<>]<<>()>)]){[((()<>){<>[]}){[{}[]){[
+(({[[({{{[{{({(){}}{{}[]})<({}[])([]<>)>}[[(<>{})]<([]()){{}()}>]}[{<{[]<>}<()()>>([{}<>]<{
+<[({{[<[{({[({[]<>}{{}[]})[{[][]}{[][]}]][[<{}[]>{[]()}]([()[]]({}<>))]}{<{[{}<>]<[]()>}<<[]()>[<>{}]>><((
+[{[{<{{[<<[[<<{}<>>>][{{{}[]}({}())}]]([{<<><>>({}{})}{{[]<>}}]{{{[]()}([]<>)}})><({{<[][]>}}){<{{()><()>}>[<
+{{({([<({(<[({{}{}}<[]{}>)]>[(((<>()){<>()]))[<({}[])(<>{})>{<<><>>{[]()}}]]){{[<(()[])<()<>>>(<()<>>)]([<{}
+[({[<(<<[{<({<{}()>{{}()}})({({})<()()>}[{[]<>}[{}{}]})><[(({}{}))(((){})[[][]])]>}<{([<[]<>>]<[{}[]]((
+[<{{{<<(<[[{<([][]){<>}>}{<[[]]{[]{}}><{<>{}}>}]<<{([]())[<>[]]}><(([]{}){[]<>})[(<>())({}<>}]>>](
diff --git a/10/solution.hs b/10/solution.hs
new file mode 100644
index 0000000..662058a
--- /dev/null
+++ b/10/solution.hs
@@ -0,0 +1,60 @@
+import Data.List
+
+main :: IO ()
+main = do
+    input <- readFile "10/input.txt"
+    let x = lines input
+    -- Problem 1
+    print $ f x
+    -- Problem 2
+    print $ g x
+    where
+        f = solve 1
+        g = solve 2
+
+-- | A syntax error type.
+data Error = Incomplete Char
+           | Corrupted Char
+           deriving
+               Show
+
+-- | Check if the error is that the found character doesn't match the
+-- | expected character.
+corrupted :: Error -> Bool
+corrupted (Corrupted _) = True
+corrupted _ = False
+
+-- | Check if the error is that the line is incomplete.
+incomplete :: Error -> Bool
+incomplete = not . corrupted
+
+solve :: Int -> [String] -> Int
+solve 1 = sum . (>>= (map score . take 1 . filter corrupted . synck []))
+solve 2 = mid . sort . map calc . filter (all incomplete) . map (synck [])
+    where 
+        calc = foldl (\a e -> (a * 5) + score e) 0
+        mid ls = ls !! (length ls `div` 2)
+
+-- | Run the syntax checker on the given line.
+synck :: [Char] -- ^ A stack of expected characters
+  -> String     -- ^ The remaining characters to check
+  -> [Error]    -- ^ A list of syntax errors found for the given line
+synck ex [] = map Incomplete ex
+synck ex (x : xs)
+    | x == '<'     = synck ('>' : ex) xs
+    | x == '{'     = synck ('}' : ex) xs
+    | x == '('     = synck (')' : ex) xs
+    | x == '['     = synck (']' : ex) xs
+    | head ex == x = synck (tail ex)  xs
+    | otherwise    = Corrupted x : synck ex xs
+
+-- | Score the severity of the error.
+score :: Error -> Int
+score (Corrupted ')')  = 3
+score (Corrupted ']')  = 57
+score (Corrupted '}')  = 1197
+score (Corrupted '>')  = 25137
+score (Incomplete ')') = 1
+score (Incomplete ']') = 2
+score (Incomplete '}') = 3
+score (Incomplete '>') = 4