hjsonpointer-0.3.0.0: README.md

# Summary

[JSON Pointer](http://tools.ietf.org/html/rfc6901) library for Haskell.

[Hackage](https://hackage.haskell.org/package/hjsonpointer) / [GitHub](https://github.com/seagreen/hjsonpointer) / [Travis CI](https://travis-ci.org/seagreen/hjsonpointer)

# Example

```haskell
{-# LANGUAGE OverloadedStrings #-}

module Main where

import           Control.Monad      (unless)
import           Data.Aeson
import qualified Data.Aeson.Pointer as P

main :: IO ()
main = do
  -- JSON Pointers must either be empty or start with a /.
  pntr1 <- case P.unescape "/foo/0" of
             Left _     -> error "Failed to construct JSON Pointer."
             Right pntr -> pure pntr

  -- We can also write JSON Pointers in Haskell.
  let pntr2 = P.Pointer [P.Token "/"]
  -- When we do this we don't have to escape / or ~ characters
  -- (as ~1 and ~0 respectively) like we do in an escaped JSON
  -- Pointer string.
  unless (P.unescape "/~1" == Right pntr2) (error "ohno!")

  print (P.resolve pntr1 document)
  print (P.resolve pntr2 document)

  where
    document :: Value
    document = object [ "foo" .= [String "bar", String "baz"]
                      , "/"   .= String "quux"
                      ]
```

Output:
```
Right (String "bar")
Right (String "quux")
```