# dag: Basic type-safe directed acyclic graphs.

This is a type-safe approach for a directed acyclic graph.

Edge construction is incremental, creating a "schema":

import Data.Graph.DAG.Edge -- | Edges are statically defined: edges = ECons (Edge :: EdgeValue "foo" "bar") $ ECons (Edge :: EdgeValue "bar" "baz") $ ECons (Edge :: EdgeValue "foo" "baz") unique -- ENil, but casted for uniquely edged graphs

The nodes are separate from edges; graph may be not connected:

data Cool = AllRight | Radical | SuperDuper graph = GCons "foo" AllRight $ GCons "bar" Radical $ GCons "baz" SuperDuper $ GNil edges

Some type tomfoolery:

*Data.Graph.DAG> :t edges edges :: EdgeSchema '['EdgeType "foo" "bar", 'EdgeType "bar" "baz", 'EdgeType "foo" "baz"] -- Type list of edges '['("foo", '["bar", "baz"]), '("bar", '["baz"])] -- potential loops 'True -- uniqueness *Data.Graph.DAG> :t getSpanningTrees $ edges getSpanningTrees $ edges :: Data.Proxy.Proxy '['Node "foo" '['Node "bar" '['Node "baz" '[]], 'Node "baz" '[]], 'Node "bar" '['Node "baz" '[]], 'Node "baz" '[]] *Data.Graph.DAG> reflect $ getSpanningTrees $ edges [Node "foo" [Node "bar" [Node "baz" []] ,Node "baz" []] ,Node "bar" [Node "baz" []] ,Node "baz" []]

This library is still very naive, but it will give us compile-time enforcement of acyclicity (and uniqueness) in these graphs - ideal for dependency graphs.

Versions [faq] | 0.0.1, 0.0.2, 0.0.2.1, 0.1, 0.1.0.1, 0.1.0.2 (info) |
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Dependencies | base (>=4.7 && <5), constraints, singletons [details] |

License | BSD-3-Clause |

Author | Athan Clark <athan.clark@gmail.com> |

Maintainer | Athan Clark <athan.clark@gmail.com> |

Source repo | head: git clone https://github.com/athanclark/dag |

Uploaded | by athanclark at Wed Jan 21 17:59:55 UTC 2015 |

Distributions | NixOS:0.1.0.2 |

Downloads | 2018 total (33 in the last 30 days) |

Rating | (no votes yet) [estimated by rule of succession] |

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Status | Docs uploaded by user Build status unknown [no reports yet] |

## Downloads

- dag-0.0.2.1.tar.gz [browse] (Cabal source package)
- Package description (as included in the package)