Copyright | (c) Andrey Mokhov 2016-2018 |
---|---|
License | MIT (see the file LICENSE) |
Maintainer | andrey.mokhov@gmail.com |
Stability | experimental |
Safe Haskell | None |
Language | Haskell2010 |
Alga is a library for algebraic construction and manipulation of graphs in Haskell. See this paper for the motivation behind the library, the underlying theory, and implementation details.
This module defines various internal utilities and data structures used throughout the library, such as lists with fast concatenation. The API is unstable and unsafe, and is exposed only for documentation.
General data structures
An abstract list data type with O(1) time concatenation (the current
implementation uses difference lists). Here a
is the type of list elements.
List
a
is a Monoid
: mempty
corresponds to the empty list and two lists
can be concatenated with mappend
(or operator <>
). Singleton
lists can be constructed using the function pure
from the Applicative
instance. List
a
is also an instance of IsList
, therefore you can use
list literals, e.g. [1,4]
::
List
Int
is the same as pure
1
<>
pure
4
; note that this requires the OverloadedLists
GHC extension. To extract plain Haskell lists you can use the toList
function from the Foldable
instance.
Data structures for graph traversal
The focus of a graph expression is a flattened represenentation of the
subgraph under focus, its context, as well as the list of all encountered
vertices. See removeEdge
for a use-case example.
focus :: ToGraph g => (ToVertex g -> Bool) -> g -> Focus (ToVertex g) Source #
Focus
on a specified subgraph.
The context of a subgraph comprises the input and output vertices outside the subgraph that are connected to the vertices inside the subgraph.