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


-- | Functional Pearl: Implicit Configurations
--   
--   This package provides an implementation of the ideas presented in the
--   paper "Functional Pearl: Implicit Configurations" by Oleg Kiselyov and
--   Chung-chieh Shan. However, the API has been modified to use
--   <tt>TypeFamilies</tt> and the implementation has been streamlined to
--   improve performance.
--   
--   The original paper can be obtained from
--   <a>http://www.cs.rutgers.edu/~ccshan/prepose/prepose.pdf</a>
--   
--   <i>Changes in 1.0</i>:
--   
--   <ul>
--   <li>Much faster implementation available that is about 50 <i>times</i>
--   faster than 0.9 and which runs purely on black magic. This version is
--   now used by default. To turn it off install with the <a>slow</a> flag.
--   If you encounter a problem with implementation, please contact the
--   author.</li>
--   </ul>
--   
--   <i>Changes in 0.9</i>:
--   
--   <ul>
--   <li>Faster internal implementation, about 40 percent faster than
--   0.8.</li>
--   <li>Removed <tt>ReifiedNum</tt>, <tt>reflectNum</tt>, and
--   <tt>reifyIntegral</tt>; <tt>reify</tt> and <tt>reflect</tt> are
--   considerably faster than the special case combinators were.</li>
--   </ul>
--   
--   <i>Changes in 0.8</i>:
--   
--   <ul>
--   <li>Switched to using type families to avoid a problem where the user
--   could cast <tt>Proxy (s a) -&gt; Proxy (s b)</tt> and get back a
--   values with the wrong type under the API in effect from 0.6. This API
--   yields a much nicer example as well.</li>
--   <li>Removed <tt>reflectT</tt> as it no longer makes sense.</li>
--   <li>Added a more advanced example <tt>example/Constraints.hs</tt>
--   using constraint kinds.</li>
--   </ul>
--   
--   <i>Changes in 0.7</i>:
--   
--   <ul>
--   <li>Uses a much simpler construction where <tt>reify</tt> now converts
--   a <tt>StablePtr</tt> to an <tt>IntPtr</tt> and reifies that directly
--   as an integral type rather than serializing and storing the StablePtr
--   as a list of bytes as proposed in the original paper.</li>
--   <li>Removed <tt>ReifiedStorable</tt> and <tt>ReifiedNums</tt>.</li>
--   <li>Since we have so many fewer classes now,
--   <tt>Data.Reflection.Internal</tt> was merged back into
--   <tt>Data.Reflection</tt></li>
--   </ul>
--   
--   <i>Changes in 0.6</i>:
--   
--   <ul>
--   <li>Removed the dependency on multiparameter type classes, functional
--   dependencies, and flexible instances, by making <tt>Reifies</tt> a
--   single parameter type class in the same fashion as
--   <tt>ReifiesStorable</tt>.</li>
--   <li>Moved the building blocks to <tt>Data.Reflection.Internal</tt> to
--   reduce API clutter.</li>
--   <li>Added <tt>reflectT</tt></li>
--   </ul>
--   
--   <i>Changes in 0.5</i>:
--   
--   <ul>
--   <li>Generalized the type signatures in reflect to allow you to pass
--   any type with kind <tt>* -&gt; *</tt> wrapped around the desired type
--   as the phantom type argument rather than just a <tt>Proxy</tt>.</li>
--   </ul>
--   
--   <i>Changes in 0.4</i>:
--   
--   <ul>
--   <li>Converted from <a>Data.Tagged</a> to using <a>Data.Proxy</a> for
--   reflection. This reduces the need for helper functions and scoped type
--   variables in user code.</li>
--   </ul>
@package reflection
@version 1.0


-- | Based on the Functional Pearl: Implicit Configurations paper by Oleg
--   Kiselyov and Chung-chieh Shan.
--   
--   <a>http://www.cs.rutgers.edu/~ccshan/prepose/prepose.pdf</a>
--   
--   The approach from the paper was modified to work with Data.Proxy and
--   to cheat by using knowledge of GHC's internal representations by
--   Edward Kmett and Elliott Hird.
--   
--   Usage reduces to using two combinators, <a>reify</a> and
--   <a>reflect</a>.
--   
--   <pre>
--   ghci&gt; reify 6 (\p -&gt; reflect p + reflect p) :: Int
--   12
--   </pre>
--   
--   The argument passed along by reify is just a <tt>data Proxy t =
--   Proxy</tt>, so all of the information needed to reconstruct your value
--   has been moved to the type level. This enables it to be used when
--   constructing instances (see <tt>examples/Monoid.hs</tt>).
module Data.Reflection
class Reified s where type family Reflected s
reflect :: Reified s => p s -> Reflected s
reify :: a -> (forall s. (Reified s, Reflected s ~ a) => Proxy s -> w) -> w