Text.Pretty.Simple
==================
[](http://travis-ci.org/cdepillabout/pretty-simple)
[](https://hackage.haskell.org/package/pretty-simple)
[](http://stackage.org/lts/package/pretty-simple)
[](http://stackage.org/nightly/package/pretty-simple)
`pretty-simple` is a pretty printer for Haskell data types that have a `Show`
instance.
For example, imagine the following Haskell data types and values:
```haskell
data Foo = Foo { foo1 :: Integer , foo2 :: [String] } deriving Show
foo :: Foo
foo = Foo 3 ["hello", "goodbye"]
data Bar = Bar { bar1 :: Double , bar2 :: [Foo] } deriving Show
bar :: Bar
bar = Bar 10.55 [foo, foo]
```
If you run this in `ghci` and type `print bar`, you'll get output like this:
```haskell
Bar {bar1 = 10, bar2 = [Foo {foo1 = 3, foo2 = ["hello","goodbye"], foo3 = 3.3},Foo {foo1 = 3, foo2 = ["hello","goodbye"], foo3 = 3.3}], bar3 = 10.55}
```
This is pretty hard to read. Imagine if there were more fields or it were even
more deeply nested. It would be even more difficult to read.
`pretty-simple` can be used to print `bar` in an easy-to-read format:
## Usage
`pretty-simple` can be easily used from `ghci` when debugging.
When using `stack` to run `ghci`, just append append the `--package` flag to
the command line to load `pretty-simple`.
```sh
$ stack ghci --package pretty-simple
```
Once you get a prompt in `ghci`, you can use `import` to get `pretty-simple`'s
`pPrint` function in scope.
```haskell
> import Text.Pretty.Simple (pPrint)
```
You can test out `pPrint` with simple data types like `Maybe` or tuples.
```haskell
> pPrint $ Just ("hello", "goodbye")
Just
( "hello"
, "goodbye"
)
```
## Features
`pretty-simple` has these features:
- Easy-to-read
- Complex data types are simple to understand.
- Color
- Prints in color using ANSI escape codes.
- It is possible to print without color by using the `pPrintNoColor`
function.
- Rainbox Parentheses
- Easy to understand deeply nested data types.
- Configurable Indentation
- Amount of indentation is configurable with the `pPrintOpt` function.
- Fast
- No problem with data types thousands of lines long.
- Works with any data type with a `Show` instance
- Some common Haskell data types have a `Show` instance that produces
non-valid Haskell code. `pretty-simple` will pretty-print even these
data types.
## Why not `(some other package)`?
Other pretty-printing packages have some combination of these defects:
- No options for printing in color.
- No options for changing the amount of indentation
- Requires every data type to be an instance of some special typeclass (instead
of just `Show`).
- Requires all `Show` instances to output valid Haskell code.
## Contributions
Feel free to open an issue or PR for any bugs/problems/suggestions/improvements.