superconstraints: Access an instance's constraints

Constraint manipulation

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Versions [RSS]	0.0.1, 0.0.2
Dependencies	base (>=4.9.1 && <4.10), constraints (>=0.9.1 && <0.10), containers (>=0.5.7.1 && <0.6), haskell-src-meta (>=0.7.0.1 && <0.8), mtl (>=2.2.1 && <2.3), tagged (>=0.8.5 && <0.9), template-haskell (>=2.11.1 && <2.12), type-eq (>=0.5 && <0.6) [details]
License	BSD-3-Clause
Copyright	Copyright (C) 2013 Ryan Trinkle
Author	Ryan Trinkle
Maintainer	Ryan Trinkle <ryan.trinkle@gmail.com
Category	Constraints
Home page	http://github.com/ryantrinkle/superconstraints
Bug tracker	http://github.com/ryantrinkle/superconstraints/issues
Source repo	head: git clone git://github.com/ryantrinkle/superconstraints.git
Uploaded	by RyanTrinkle at 2017-05-26T21:12:05Z
Distributions
Reverse Dependencies	1 direct, 0 indirect [details]
Downloads	1536 total (12 in the last 30 days)
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Status	Docs uploaded by user [build log] All reported builds failed as of 2017-05-26 [all 2 reports]

A way of inferring instance constraints given an instance.

Suppose you have a class like this:

class C a

instance C a => C [a]

Normally, given C [a], you cannot obtain C a; however, superconstraints allows you to add that capability:

class HasSuper (C a) => C a

instance C a => C [a]
makeSuper "C [a]"

Then, you can retrieve the superconstraint by doing:

case super (Proxy :: Proxy (C [a])) of
  Dict -> ...

The superconstraint dictionary will include all of the constraints required by the instance.