seanmor5 / tree

Tree

Small library for working with nested tree-like data structures.

Each tree-like data structure implements the Tree.Def protocol which provides implementations for traversing and reducing the nested tree-like data structure. There are default implementations for List, Tuple, and Map.

Installation

def deps do
  [
    {:tree, "~> 0.1.0", github: "seanmor5/tree"}
  ]
end

Examples

Consider the following complex nested data structure:

tree = %{a: {1, [2, 3]}, b: [%{c: {2, 3}, d: [5]}], c: %{d: [6, {7, 8}, 9]}}

Tree treats values which don't implement the Tree.Def protocol as leaves, so you can apply arbitrary transformations and reductions to leaves without having to deal with nesting. Most functions you're familiar with in Enum work in Tree:

Tree.map(tree, fn x -> x + 1 end)
# %{a: {2, [3, 4]}, b: [%{c: {3, 4}, d: [6]}], c: %{d: [7, {8, 9}, 10]}}

Tree.reduce(tree, 0, fn x, acc -> x + acc end)
# 46

Tree.flat_map(tree, fn x -> x + 1 end)
[2, 3, 4, 3, 4, 6, 7, 8, 9, 10]

If you have multiple nested data structures with the same tree-like structure, you can easily apply zip_with/3 or zip_reduce/4 to transform the trees as a pair:

tree1 = %{a: {1, [2, 3]}, b: [%{c: {2, 3}, d: [5]}], c: %{d: [6, {7, 8}, 9]}}
tree2 = %{a: {9, [10, 11]}, b: [%{c: {12, 13}, d: [14]}], c: %{d: [15, {16, 17}, 18]}}
Tree.zip_with(tree1, tree2, fn x, y -> x + y end)
# %{a: {10, [12, 14]}, b: [%{c: {14, 16}, d: [19]}], c: %{d: [21, {23, 25}, 27]}}

tree1 = %{a: {1, [2, 3]}, b: [%{c: {2, 3}, d: [5]}], c: %{d: [6, {7, 8}, 9]}}
tree2 = %{a: {9, [10, 11]}, b: [%{c: {12, 13}, d: [14]}], c: %{d: [15, {16, 17}, 18]}}
Tree.zip_reduce(tree1, tree2, 0, fn x, y, acc -> x + y + acc end)
# 181