https://github.com/weavejester/meta-merge

A standalone implementation of Leiningen's meta-merge function
https://github.com/weavejester/meta-merge

Last synced: about 1 month ago
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A standalone implementation of Leiningen's meta-merge function

• Host: GitHub
• URL: https://github.com/weavejester/meta-merge
• Owner: weavejester
• Created: 2014-10-05T19:42:27.000Z (about 10 years ago)
• Default Branch: master
• Last Pushed: 2023-11-13T14:49:33.000Z (about 1 year ago)
• Last Synced: 2024-10-28T13:37:48.908Z (about 2 months ago)
• Language: Clojure
• Size: 12.7 KB
• Stars: 105
• Watchers: 5
• Forks: 5
• Open Issues: 2
• Metadata Files:
  • Readme: README.md

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README

        
# Meta-Merge

[![Build Status](https://travis-ci.org/weavejester/meta-merge.svg?branch=master)](https://travis-ci.org/weavejester/meta-merge)

This is a standalone implementation of the [Leiningen][] `meta-merge`

function. It's particularly useful for merging configuration maps.

[Leiningen]: https://github.com/technomancy/leiningen

## Installation

To install, add the following to your project `:dependencies`:

    [meta-merge "1.0.0"]

## Usage

The `meta-merge` function recursively merges two data structures.

```clojure

(require '[meta-merge.core :refer [meta-merge]])

(meta-merge {:a [:b :c]} {:a [:d]})

=> {:a [:b :c :d]}

```

## Metadata

Metadata hints can be provided to override the default behavior:

### Prepend

When `meta-merge` is called with a hash-map that has `^:prepend` on it, the

function  will take the values on the right and prepend them to the set on the

left (the default would **append** them as you can see above). You can see this

below.

```clojure

(meta-merge {:a [:b :c]} {:a ^:prepend [:d]})

=> {:a [:d :b :c]}

```

### Replace

When `meta-merge` is called with a hash-map that has `^:replace` on it, the

function will take the values on the right and completely replace the ones on

the left. You can see this below:

```clojure

(meta-merge {:a [:b :c]} {:a ^:replace [:d]})

=> {:a [:d]}

```

With replace the map to the right takes precedence.

### Displace

When `meta-merge` is called with a hash-map that has `^:displace` on it, the

function will take the values on the right, only if there are no values on the

left. You can see this below:

```clojure

(meta-merge {:a [:b :c]} {:a ^:displace [:d]})

=> {:a [:b :c]}

```

With displace the map to the left takes precedence. This makes displace a

good solution for default values.

## License

Copyright © 2016 Phil Hagelberg, James Reeves and all the Leiningen

[contributors][].

Distributed under the Eclipse Public License either version 1.0 or (at

your option) any later version.

[contributors]: https://github.com/technomancy/leiningen/graphs/contributors