- headers ALIST #!optional HEADERSprocedure
This creates a header object based on an input list.
Requests and responses contain HTTP headers wrapped in a special header-object to ensure they are properly normalized.
The input list has header names (symbols) as keys, and lists of values as values:
(headers `((host ("example.com" . 8080)) (accept #(text/html ((q . 0.5))) #(text/xml ((q . 0.1))))) old-headers)
This adds the named headers to the existing headers in old-headers. The host header is a pair of hostname/port. The accept header is a list of allowed mime-type symbols.
As can be seen here, optional parameters or "attributes" can be added to a header value by wrapping the value in a vector of length 2. The first entry in the vector is the header value, the second is an alist of attribute name/value pairs.