```coffeescript
Immutable = require 'immutable'
React = require 'react'
Router = require 'react-router'

utils = require '../utils.coffee'
URL = require '../url.coffee'

module.exports = React.createClass
	displayName: 'Link'
	render: ->
		props = Immutable.fromJS(@props).toJS()
		if props.lang
			props.params.lang = props.lang
		if !props.to
			if props.href
				href = props.href
			else
				href = URL.getPath props.params
			props.to = URL.getHref href, props.params
		React.createElement Router.Link, props```

Set hreflang and rel="alternate" on Link.
user
```coffeescript
Immutable = require 'immutable'
React = require 'react'
Router = require 'react-router'

utils = require '../utils.coffee'
URL = require '../url.coffee'

module.exports = React.createClass
	displayName: 'Link'
	render: ->
		props = Immutable.fromJS(@props).filterNot(
			utils.keyIn 'lang', 'href'
		).toJS()
		if @props.lang
			props.params.lang = @props.lang
			props.hrefLang = @props.lang
		if !props.to
			if @props.href
				href = @props.href
			else
				href = URL.getPath props.params
				props.rel = 'alternate'
			props.to = URL.getHref href, props.params
		React.createElement Router.Link, props```
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