第18回オフラインリアルタイムどう書くの参考問題を Haskell で解く

第18回オフラインリアルタイムどう書くの参考問題 を解きました。

http://qiita.com/Nabetani/items/373105e7fafd12f5e9fd

```hs
foldBase val (x:xs)
  | x == 'F' = val ++ foldBase val xs
  | x == 'R' = reverse(invert val) ++ foldBase val xs
  | otherwise = x : foldBase val xs
foldBase _ [] = ""

invert ('F':xs) = 'R' : invert xs
invert ('R':xs) = 'F' : invert xs
invert ('m':xs) = 'V' : invert xs
invert ('V':xs) = 'm' : invert xs
invert [] = ""

foldL = foldBase "RVF"
foldJ = foldBase "FVR"
foldZ = foldBase "FmRVF"
foldU = foldBase "RVFVR"
foldS = foldBase "FVRmF"

filter' = filter(\x -> x == 'm' || x == 'V')

foldX x
  | x == 'L' = foldL
  | x == 'J' = foldJ
  | x == 'Z' = foldZ
  | x == 'U' = foldU
  | x == 'S' = foldS

solve xs = filter' $ foldl (\acc x -> foldX x acc) "F" xs

test input expected
  | solve input == expected = putStrLn "OK"
  | otherwise = putStrLn $ "NG : " ++ input

main = do
  test "JZ" "mVVmV"
  test "J" "V"
  test "L" "V"
  test "Z" "mV"
  test "U" "VV"
  test "S" "Vm"
  test "JL" "VVm"
  test "JS" "VmVVm"
  test "JU" "VVVmm"
  test "LU" "mmVVV"
  test "SL" "VVmmV"
  test "SS" "VmVVmmVm"
  test "SU" "VVVmmmVV"
  test "SZ" "mVVmVmmV"
  test "UL" "mVVVm"
  test "UU" "mmVVVVmm"
  test "UZ" "mVVmVVmV"
  test "ZJ" "VmmVV"
  test "ZS" "VmmVmVVm"
  test "ZZ" "mVmmVVmV"
  test "JJJ" "VVmVVmm"
  test "JJZ" "mVVmVVmVmmV"
  test "JSJ" "VVmmVVmVVmm"
  test "JSS" "VmVVmmVmVVmVVmmVm"
  test "JUS" "VmVVmVVmVVmmVmmVm"
  test "JUU" "mmVVVVmmVVVmmmmVV"
  test "JUZ" "mVVmVVmVVmVmmVmmV"
  test "LJJ" "VmmVVVm"
  test "LLS" "VmmVmVVmVVm"
  test "LLU" "mmmVVVmmVVV"
  test "LLZ" "mVmmVVmVVmV"
  test "LSU" "mmVVVmmmVVVVmmmVV"
  test "LSZ" "mVVmVmmVVmVVmVmmV"
  test "LZL" "mmVVmVVmmVV"
  test "LZS" "VmmVmVVmVVmmVmVVm"
  test "LZU" "mmmVVVmmVVVmmmVVV"
  test "SJL" "VVmVVmmmVVm"
  test "SLU" "mmVVVVmmmVVmmmVVV"
  test "SLZ" "mVVmVVmVmmVmmVVmV"
  test "SSU" "VVVmmmVVVmmVVVmmmmVVVmmmVV"
  test "SUJ" "mVVVmVVmmmVmmVVVm"
  test "SUS" "VmVVmVVmVVmmVmmVmmVmVVmVVm"
  test "SZZ" "mVmmVVmVVmVmmVVmVmmVmmVVmV"
  test "UJJ" "VmmVVVmVVmm"
  test "ULU" "mmmVVVmmVVVVmmmVV"
  test "ULZ" "mVmmVVmVVmVVmVmmV"
  test "UUU" "VVmmmmVVVmmVVVVmmVVVmmmmVV"
  test "ZJU" "VVVmmmVVmmmVVVVmm"
  test "ZLS" "VmVVmmVmmVmVVmVVm"
  test "ZSJ" "VVmmVmmVVmmVVVmmV"
  test "ZUJ" "mVVVmmVmmmVVmVVVm"
  test "JJLJ" "mVVVmmVVmVVmmmV"
  test "JLJJ" "VmmVVVmVVmmmVVm"
  test "JLJL" "VmmVVVmVVmmmVVm"
  test "LJJL" "VVmmVmmVVVmVVmm"
  test "LLJJ" "VmmmVVmVVmmVVVm"
  test "SZUS" "VmVVmVVmmVmmVmmVmVVmVVmVVmVVmmVmmVmmVmVVmVVmVVmmVmmVmmVmVVmVVmmVmmVmmVmVVmVVmVVm"
  test "ULLS" "VmmVmmVmVVmVVmmVmVVmVVmVVmmVmmVmVVm"
  test "JJJJZJ" "VmmVVVmmVVmVVmmVVmmmVVmVVmmVVVmmVVmmVmmVVmmmVVmVVmmVVVmmVVmVVmmVVmmmVVmmVmmVVVmmVVmmVmmVVmmmVVm"
  test "JULLLJ" "mmVmmVVmmmVVmVVVmmVmmVVVmmVVmVVVmmVmmVVmmmVVmVVVmmVmmVVVmmVVmVVmmmVmmVVmmmVVmVVmmmVmmVVVmmVVmVV"
  test "LJJJUL" "mVVVmVVmmmVVmVVVmmVmmmVmmVVVmVVmmmVmmVVVmmVmmmVVmVVVmVVmmmVVmVVVmmVmmmVVmVVVmVVmmmVmmVVVmmVmmmV"
  test "LJSJJL" "VVmVVmmVVVmmVmmmVVmVVmmmVVmmVmmVVVmVVmmmVVmmVmmVVVmVVmmVVVmmVmmmVVmVVmmVVVmmVmmVVVmVVmmmVVmmVmm"
  test "LZLLLJ" "mmVmmVVmmmVVmVVmmmVmmVVVmmVVmVVVmmVmmVVmmmVVmVVVmmVmmVVVmmVVmVVmmmVmmVVmmmVVmVVVmmVmmVVVmmVVmVV"
  test "SJJJJL" "VVmVVmmVVVmmVmmVVVmVVmmmVVmmVmmVVVmVVmmVVVmmVmmmVVmVVmmmVVmmVmmmVVmVVmmVVVmmVmmVVVmVVmmmVVmmVmm"
  test "ZLJLJL" "VmmVVVmmVmmmVVmVVmmVVVmVVmmmVVmmVmmVVVmmVmmmVVmmVmmVVVmVVmmmVVmVVmmVVVmmVmmmVVmVVmmVVVmVVmmmVVm"
```