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The latest version of reflection is 2.1.8-0.

reflection

Version 0.7 revision 0 uploaded by EdwardKmett.

Package meta

Synopsis
Functional Pearl: Implicit Configurations
Description

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 only one extension: Rank2Types

Usage reduces to using two combinators.

reify :: a -> (forall s. Reified s => Proxy (s a) -> w) -> w
reflect :: Reified s => p (s a) -> a
ghci> reify 6 (\p -> reflect p + reflect p)
12

The argument passed along by reify is just a data Proxy t = Proxy, 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 examples/Monoid.hs). An additional combinator that may be more useful when building instances is also supplied.

reflectT :: Reified s => p s a -> a

Changes in 0.7:

  • Uses a much simpler construction where reify now converts a StablePtr to an IntPtr 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.

  • Removed ReifiedStorable and ReifiedNums.

  • Since we have so many fewer classes now, Data.Reflection.Internal was merged back into Data.Reflection

Changes in 0.6:

  • Removed the dependency on multiparameter type classes, functional dependencies, and flexible instances, by making Reifies a single parameter type class in the same fashion as ReifiesStorable.

  • Moved the building blocks to Data.Reflection.Internal to reduce API clutter.

  • Added reflectT

Changes in 0.5:

  • Generalized the type signatures in reflect to allow you to pass any type with kind * -> * wrapped around the desired type as the phantom type argument rather than just a Proxy.

Changes in 0.4:

  • Converted from Data.Tagged to using Data.Proxy for reflection. This reduces the need for helper functions and scoped type variables in user code.

Author
Edward A. Kmett, Oleg Kiselyov and Chung-chieh Shan
Bug reports
n/a
Category
Data, Reflection, Dependent Types
Copyright
2009 Edward A. Kmett, 2004 Oleg Kiselyov and Chung-chieh Shan
Homepage
http://www.cs.rutgers.edu/~ccshan/prepose/prepose.pdf
Maintainer
Edward A. Kmett <ekmett@gmail.com>
Package URL
n/a
Stability
experimental

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