cabal exec -- ghc --make scanner.hs
./scanner input.json output.html

Origin Json File

{
    "quiz": {
        "sport": {
            "q1": {
                "question": "Which one is correct team name in NBA?",
                "options": [
                    "New York Bulls",
                    "Los Angeles Kings",
                    ...
                ],
                "answer": "Huston Rocket",
                "age": 31,
                "case": true
            }
        },
        ...
    }
}

HTML opened in browser

• About $ and .

• Maybe and Just

• IO _ when return type is IO _, use <- to assign it to a variable

  addOne :: Int -> IO Int
  addOne x = do
      return x 
  
  main = do
      value <- addOne 1
      print(value)

• unusual show

  > show '"'
  "'\"'" :: String
  > show '\\'
  "\\\\" :: String
  > show 'x'
  "'x'" :: String

  if want to convert Char to String

  > ['x']
  "x" :: [Char]

regex cheat sheet Install

$ cabal install regex-pcre

Error may occur

Wrap.hsc:148:10: fatal error: 'pcre.h' file not found
#include <pcre.h>

solution for mac

brew install pcre
cabal install regex-pcre

Manage packages in local directroy

cabal sandbox init

to use ghci with packages with local sandboxs

# For GHC < 7.6
$ ghci -no-user-package-conf -package-conf .cabal-sandbox/x86_64-osx-ghc-8.2.2-packages.conf.d

to comile hs file with local sandboxs

cabal exec -- ghc --make myhaskell.hs