GHC.Data.UnionFind

ghc-9.2.5: The GHC API

Safe Haskell | Safe-Inferred
Language | Haskell2010

GHC.Data.UnionFind

Synopsis

- newtype Point s a = Point (STRef s (Link s a))
- writePoint :: Point s a -> Link s a -> ST s ()
- readPoint :: Point s a -> ST s (Link s a)
- data Link s a
  - = Info !(STRef s Int) !(STRef s a)
  - | Link !(Point s a)
- fresh :: a -> ST s (Point s a)
- repr :: Point s a -> ST s (Point s a)
- find :: Point s a -> ST s a
- union :: Point s a -> Point s a -> ST s ()
- equivalent :: Point s a -> Point s a -> ST s Bool

# Documentation

newtype Point s a Source #

A variable which can be unified; alternately, this can be thought of as an equivalence class with a distinguished representative.

Constructors

Point (STRef s (Link s a)) |

#### Instances

Instances details

Eq (Point s a) Source # |
Instance details Defined in GHC.Data.UnionFind Methods (==) :: Point s a -> Point s a -> Bool # (/=) :: Point s a -> Point s a -> Bool #

writePoint :: Point s a -> Link s a -> ST s () Source #

Mutable write to a `Point`

readPoint :: Point s a -> ST s (Link s a) Source #

Read the current value of `Point`.

data Link s a Source #

The internal data structure for a `Point`, which either records the representative element of an equivalence class, or a link to the `Point` that actually stores the representative type.

Constructors

Info !(STRef s Int) !(STRef s a) |
Link !(Point s a) |

fresh :: a -> ST s (Point s a) Source #

Create a fresh equivalence class with one element.

repr :: Point s a -> ST s (Point s a) Source #

Flatten any chains of links, returning a `Point` which points directly to the canonical representation.

find :: Point s a -> ST s a Source #

Return the canonical element of an equivalence class `Point`.

union :: Point s a -> Point s a -> ST s () Source #

Unify two equivalence classes, so that they share a canonical element. Keeps the descriptor of point2.

equivalent :: Point s a -> Point s a -> ST s Bool Source #

Test if two points are in the same equivalence class.