type-level-sets: Type-level sets and finite maps (with value-level counterparts)

This is a package candidate release! Here you can preview how this package release will appear once published to the main package index (which can be accomplished via the 'maintain' link below). Please note that once a package has been published to the main package index it cannot be undone! Please consult the package uploading documentation for more information.

[maintain] [Publish]

This package provides type-level sets (no duplicates, sorted to provide a normal form) via Set and type-level finite maps via Map, with value-level counterparts.

Described in the paper "Embedding effect systems in Haskell" by Dominic Orchard and Tomas Petricek http://www.cl.cam.ac.uk/~dao29/publ/haskell14-effects.pdf (Haskell Symposium, 2014). This version now uses Quicksort to normalise the representation.

Here is a brief example for finite maps:

import Data.Type.Map

type instance Combine Int Int = Int
instance Combinable Int Int where
combine x y = x + y

foo :: Map '["x" :-> Int, "z" :-> Bool, "w" :-> Int]
foo = Ext (Var :: (Var "x")) 2
$ Ext (Var :: (Var "z")) True
$ Ext (Var :: (Var "w")) 5
$ Empty

bar :: Map '["y" :-> Int, "w" :-> Int]
bar = Ext (Var :: (Var "y")) 3
$ Ext (Var :: (Var "w")) 1
$ Empty

foobar = foo union bar

The Map type for foobar here shows the normalised form (sorted with no duplicates). The type signatures is commented out as it can be infered. Running the example we get:

> >>> foobar
> {w :-> 6, x :-> 2, y :-> 3, z :-> True}

Thus, we see that the values for "w" are added together.

For sets, here is an example:

import GHC.TypeLits
import Data.Type.Set
type instance Cmp (Natural n) (Natural m) = CmpNat n m

data Natural (a :: Nat) where
Z :: Natural 0
S :: Natural n -> Natural (n + 1)

foo = asSet $ Ext (S Z) (Ext (S (S (S Z))) (Ext Z Empty))

bar = asSet $ Ext (S (S Z)) (Ext (S Z) (Ext (S Z) Empty))

foobar = foo union bar

Note the types here are all inferred.

Properties

Versions 0.5, 0.6, 0.6.1, 0.7, 0.8.0.0, 0.8.0.0, 0.8.5.0, 0.8.6.0, 0.8.7.0, 0.8.9.0
Change log None available
Dependencies base (<5), ghc-prim [details]
License BSD-3-Clause
Copyright 2013-16 University of Cambridge
Author Dominic Orchard
Maintainer Dominic Orchard
Category Type System, Data Structures
Source repo head: git clone https://github.com/dorchard/type-level-sets
Uploaded by DominicOrchard at 2016-09-04T20:46:02Z

Modules

[Index]

Downloads

Maintainer's Corner

Package maintainers

For package maintainers and hackage trustees