Tree Builder

Tools for building a tree from a string or a list of blocks as well as some other tools:

• Tree.Blocks: transform a string into a list of blocks

• Tree.Build: the main module; build a tree from a string or a list
  of blocks.

• Tree.Lib: preOrder, levelOrder, edges. The latter transforms Tree a to List (a, a) where the latter represents a list of edges of the tree

• Tree.Random: generate random trees

• Tree.Svg: helper functions for rendering graphs (a data structure derived from a tree that can be rendered to SVG).

• Tree.Transform: transform a Tree to a Graph, as in the preceding item.

See the code in app/src/Main.elm for an example of building a tree from text and rendering it to Svg.

Building Trees

A tree is represented in text as an outline:

The Book of Monsters
  Under the Earth
     Extinct Monsters
     Living Monsters
  On Dry Land
     Extinct Monsters
     Living Monsters
     Nice Monsters
  Imaginary Monsters

This root node is "The Book of Monsters." It has three child nodes, "Under the Earth," "On Dry Land," and "Imaginary Monsters." A tree like this where nodes can have more than two children is called a "rose tree."

Example:


    > Import Tree.Build as Build


    > data = "1\n 2\n 3\n 4\n5\n 6\n 7"


    > Build.fromString "?" identity data
      Tree "0" [
            Tree "1" [Tree "2" [],Tree "3" [], Tree "4" []]
          , Tree "5" [Tree "6" [],Tree "7" []]
          ]

The first argument of fromString is a label for a default node. The second argument, of type (String -> node), tells how to build a node from a string representation of that node. Here we use the representation of rose trees of elm/rose-tree.