# @unction/treeify

![Tests][BADGE_TRAVIS]
![Stability][BADGE_STABILITY]
![Dependencies][BADGE_DEPENDENCY]

> Array<FoldFunctionType<A, B>> => Array<A> => TreeType<C>

This takes a list of functions (the folders) and an array of objects or an
object of objects (the collection) to create a tree. Each function in
the list of folders will in some way return a new object. All of the objects
produced are then turned into a final tree.

``` javascript
const collection = [
  {
    id: "a1",
    type: "resources",
    attributes: {
      version: "v1",
      namespace: "accounts",
    }
  },
  {
    id: "a2",
    type: "resources",
    attributes: {
      version: "v1",
      namespace: "accounts",
    }
  },
  {
    id: "b1",
    type: "resources",
    attributes: {
      version: "v1",
      namespace: "profiles",
    }
  },
  {
    id: "b1",
    type: "resources",
    attributes: {
      version: "v2",
      namespace: "profiles",
    }
  }
]
````

The order goes from outer layer to deeper layer, so in this case the outer
level properties will be based on `key("type")`, and the deepest layer
properties will be based on `key("id")`.

``` javascript
const functions =

treeify(
  [
    groupBy(key("type")),
    groupBy(keyChain(["attributes", "namespace"])),
    groupBy(keyChain(["attributes", "version"])),
    indexBy(key("id")),
  ]
)(
  collection
)
```

The resulting object looks like this:

``` javascript
{
  resources: {
    accounts: {
      v1: {
        a1: {
          id: "a1",
          type: "resources",
          attributes: {
            version: "v1",
            namespace: "accounts",
          }
        },
        a2: {
          id: "a2",
          type: "resources",
          attributes: {
            version: "v1",
            namespace: "accounts",
          }
        }
      }
    },
    profiles: {
      v1: {
        b1: {
          id: "b1",
          type: "resources",
          attributes: {
            version: "v1",
            namespace: "profiles",
          }
        }
      },
      v2: {
        b1: {
          id: "b1",
          type: "resources",
          attributes: {
            version: "v2",
            namespace: "profiles",
          }
        }
      }
    }
  }
}
```

[BADGE_TRAVIS]: https://img.shields.io/travis/unctionjs/treeify.svg?maxAge=2592000&style=flat-square
[BADGE_STABILITY]: https://img.shields.io/badge/stability-strong-green.svg?maxAge=2592000&style=flat-square
[BADGE_DEPENDENCY]: https://img.shields.io/david/unctionjs/treeify.svg?maxAge=2592000&style=flat-square