nicify is a tool for pretty printing the default formatting of Show instances. It is especially useful when dumping data during debugging.

Example

Given main.hs:

    data X = A [X] | B String | C (X, X)
      deriving (Show)
    main = print $
      A [B "one", B "two", A [ C (B "three", B "three prime"), B "woop woop" ]]

you would typically get:

    >>> runhaskell main.hs
    A [B "one",B "two",A [C (B "three",B "three prime"),B "woop woop"]]

not so with nicify:

    >>> runhaskell main.hs | nicify
    A [
        B "one",
        B "two",
        A [
            C (B "three",
            B "three prime"),
            B "woop woop"
        ]
    ]

Looking for nicify as a library function for your haskell programs? Check out github.com/scravy/nicify-lib!