The reflection package
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.
Properties
| Versions | 0.0.0, 0.1.0, 0.1.1, 0.2.0, 0.3.0, 0.3.1, 0.3.2, 0.3.3, 0.3.5, 0.4.0, 0.4.0.1, 0.4.0.2, 0.4.1, 0.4.1.1, 0.5, 0.5.0.1, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.1.1, 1.1.2, 1.1.3, 1.1.4, 1.1.5, 1.1.5.1, 1.1.6, 1.1.7, 1.2.0.1, 1.3, 1.3.1, 1.3.2 |
|---|---|
| Dependencies | base (4.*), tagged (≥0.2.3 & <0.3) |
| License | BSD3 |
| Copyright | 2009 Edward A. Kmett, 2004 Oleg Kiselyov and Chung-chieh Shan |
| Author | Edward A. Kmett, Oleg Kiselyov and Chung-chieh Shan |
| Maintainer | Edward A. Kmett <ekmett@gmail.com> |
| Stability | experimental |
| Category | Data, Reflection, Dependent Types |
| Home page | http://www.cs.rutgers.edu/~ccshan/prepose/prepose.pdf |
| Source repository | git clone git://github.com/ekmett/reflection.git |
| Upload date | Sat Apr 7 00:56:12 UTC 2012 |
| Uploaded by | EdwardKmett |
| Built on | ghc-7.4 |
| Distributions | NixOS: 1.3.2, Debian: 1.2.0.1, FreeBSD: 1.3.2 |
Modules
- Data
Downloads
- reflection-0.7.tar.gz (Cabal source package)
- package description (included in the package)