-- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/


-- | Pretty error messages for runtime invariants
--   
@package pretty-error
@version 0.1.0.0


-- | Pretty runtime error messages
--   
--   These functions can be used to raise clear, understandable error
--   messages for when your program violates an invariant at runtime.
--   
--   In particular, <a>assertRight</a> handles a common case where we
--   "know" that a particular <a>Either</a> is going to be <a>Right</a>,
--   and so we want to be able to unpack the value but also provide a
--   high-quality error message if the value does somehow turn out to be a
--   <a>Left</a>.
module PrettyError

-- | Assert that value is <a>Right</a>. Throw error if it's <a>Left</a>.
--   
--   The first argument is a message which can be used to explain why this
--   error should not have happened.
--   
--   Use <a>fromRight</a> if you don't want to provide a message.
--   
--   <pre>
--   &gt;&gt;&gt; assertRight "Artificial example" (Right 5)
--   5
--   </pre>
--   
--   <pre>
--   &gt;&gt;&gt; assertRight "Artificial example" (Left "error message")
--   *** Exception: Artificial example: "error message"
--   </pre>
assertRight :: Show a => Text -> Either a b -> b

-- | Extract the value out of a <a>Right</a>, or throw an error from a
--   <a>Left</a> made up of the pretty-printed <a>Left</a> value.
--   
--   Most of the time you should use <a>assertRight</a>, since that allows
--   you to provide a message, which will help to debug the problem.
--   
--   <pre>
--   &gt;&gt;&gt; fromRight (Right 5)
--   5
--   </pre>
--   
--   <pre>
--   &gt;&gt;&gt; fromRight (Left 4)
--   *** Exception: 4
--   </pre>
fromRight :: Show a => Either a b -> b

-- | Pretty print a variable to <a>Text</a>
--   
--   Although not strictly related to error messages, this is a handy
--   function to have around if you are using <a>Text.Show.Pretty</a> and
--   <tt>OverloadedStrings</tt>.
ppText :: Show a => a -> Text

-- | Raise an error with a pretty-printed value.
--   
--   <pre>
--   &gt;&gt;&gt; prettyError ["foo","bar","baz"]
--   *** Exception: [ "foo" , "bar" , "baz" ]
--   </pre>
prettyError :: Show a => a -> b