How to concatenate parts to a mapping key

I’m using the map feature to redirect from one path to another looking up a list in an external file. This is how that work:

http-request redirect code 301 location %[capture.req.uri,map(/etc/haproxy/] if { capture.req.uri,map(/etc/haproxy/ -m found }

Now I need to enhance that such that the key which is capture.req.uri in the above example will now be the domain AND the path so I wonder how I could concatenate those 2 parts (hdr(host) and capture.req.uri) into one string to work as the key for the lookups.

Trying to bump this to the top hoping for some attention.

Found it: the ACL base is doing exactly what I was looking for.