gistfile1.hs

module Main where

  import Prelude
  import Parsing
  import Either

  foreign import data JSON :: *

  foreign import toJSON "function toJSON (obj) { return obj; }" :: forall a. a -> JSON
  foreign import showJSON "function showJSON (obj) { return JSON.stringify(obj); }" :: JSON -> String

  foreign import readProp "function readProp (k) { \
                      \  return function(typeName) {\
                      \    return function (obj) { \
                      \      if (obj.hasOwnProperty(k) && typeof (obj[k]) == typeName) { \
                      \        return Either.Right(obj[k]);\
                      \      } \
                      \      return Either.Left('Unknown property ' + k + ''); \
                      \    }; \
                      \  }; \
                      \};" :: forall a. String -> String -> JSON -> Either String a

  instance Prelude.Show JSON where
    show = showJSON

  toParser :: forall a s. (s -> Either String a) -> Parser s a
  toParser p = Parser $ \x -> case (p x) of
    (Left err) -> Left $ parseError err
    (Right res) -> Right $ parseResult x res

  prop :: forall a. String -> String -> Parser JSON a
  prop k ty = toParser $ readProp k ty

  str :: String -> Parser JSON String
  str = flip prop "string"

  num :: String -> Parser JSON Number
  num = flip prop "number"

  bool :: String -> Parser JSON Boolean
  bool = flip prop "boolean"

  parser :: Parser JSON String
  parser = str "foo"

  main = do
    let obj = toJSON { foo: "hello", bar: true, baz: 1 }
    case runParser parser obj of
      Left (ParseError err) -> Trace.print err.message
      Right (ParseResult { result = res }) -> Trace.print res