Redirect from root to subfolder but retain root-URL

I would like the content of someexample.com to be taken from a sub directory with .htaccess but keep the main URL unchanged, like this:

Entered URL: someexample.com

Shown content: http://ift.tt/1SLPqZD

Still shown URL: someexample.com

I know that there are several similar questions/solutions out there for this but none seems to work for me because it's either meant for subdomains or external domains.

Thank you Fabian