https://github.com/elm-community/graph

Functional Graph Library in Elm.
https://github.com/elm-community/graph

Last synced: 3 months ago
JSON representation

Functional Graph Library in Elm.

• Host: GitHub
• URL: https://github.com/elm-community/graph
• Owner: elm-community
• License: mit
• Fork: true (sgraf812/elm-graph)
• Created: 2016-06-08T01:11:42.000Z (over 8 years ago)
• Default Branch: master
• Last Pushed: 2024-06-14T11:20:30.000Z (5 months ago)
• Last Synced: 2024-06-19T11:39:41.783Z (5 months ago)
• Language: Elm
• Homepage: http://package.elm-lang.org/packages/elm-community/graph/latest
• Size: 156 KB
• Stars: 60
• Watchers: 6
• Forks: 16
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

README

        
# Graph [![Build Status](https://travis-ci.org/elm-community/graph.svg)](https://travis-ci.org/elm-community/graph)

An neat graph library for Elm.

Got confused about what to wear when putting on shoes? This will help you out:

```elm

dressUp : Graph String () -- node labels are strings, edge labels are empty

dressUp =

  let

    nodes =

      [ Node 0 "Socks"

      , Node 1 "Undershirt"

      , Node 2 "Pants"

      , Node 3 "Shoes"

      , Node 4 "Watch"

      , Node 5 "Shirt"

      , Node 6 "Belt"

      , Node 7 "Tie"

      , Node 8 "Jacket"

      ]

    e from to =

      Edge from to ()

    edges =

      [ e 0 3 -- socks before shoes

      , e 1 2 -- undershorts before pants

      , e 1 3 -- undershorts before shoes

      , e 2 3 -- pants before shoes

      , e 2 6 -- pants before belt

      , e 5 6 -- shirt before belt

      , e 5 7 -- shirt before tie

      , e 6 8 -- belt before jacket

      , e 7 8 -- tie before jacket

      ]

  in

    Graph.fromNodesAndEdges nodes edges

iWantToWearShoes: List String

iWantToWearShoes =

  Graph.guidedDfs

    Graph.alongIncomingEdges            -- which edges to follow

    (Graph.onDiscovery (\ctx list ->    -- append node labels on discovery

      ctx.node.label :: list))

    [3 {- "Shoes" NodeId -}]            -- start with the node labelled "Shoes"

    []                                  -- accumulate starting with the empty list

    dressUp                             -- traverse our dressUp graph from above

    |> Tuple.first                      -- ignores the untraversed rest of the graph

iWantToWearShoes == ["Pants", "Undershorts", "Socks", "Shoes"]

```

So better wear pants, undershorts, pants and socks with your shoes.

(In case you wonder: There is also a `topologicalSort` function which can compute

valid linear orderings)

# Credits

I was inspired by Martin Erwig's original idea realized in the

[functional graph library](http://hackage.haskell.org/package/fgl-5.5.2.1), but

I also tried to keep it as simple as possible, bringing the neatness of Elm to

graph libraries.