I think I got it. Here’s footer.html
{{ $links := .Site.Data.socialmedia.accounts }}
<footer>
<small>Copyright {{now.Format "2006"}} {{ .Site.Params.author }}. {{partial "social.html" (dict "links" $links)}}</small>
</footer>
Here’s social.html
<ul>
{{range .links}}
<li><a href="{{ .url }}">{{ .name }}</a></li>
{{end}}
</ul>
I am curious how it might be done without the dict function.