The type of a group of header fields.

The type of a lowercase header name.

The type of a header value.

empty is the empty collection of header fields.

of_list assoc is a collection of header fields defined by the association list assoc. of_list assumes the order of header fields in assoc is the intended transmission order. The following equations should hold:

• to_list (of_list lst) = lst
• get (of_list [("k", "v1"); ("k", "v2")]) "k" = Some "v2".

of_list assoc is a collection of header fields defined by the association list assoc. of_list assumes the order of header fields in assoc is the reverse of the intended trasmission order. The following equations should hold:

• to_list (of_rev_list lst) = List.rev lst
• get (of_rev_list [("k", "v1"); ("k", "v2")]) "k" = Some "v1".

to_list t is the association list of header fields contained in t in transmission order.

to_rev_list t is the association list of header fields contained in t in reverse transmission order.

add t ?sensitive name value is a collection of header fields that is the same as t except with (name, value) added at the end of the trasmission order. Additionally, sensitive specifies whether this header field should not be compressed by HPACK and instead encoded as a never-indexed literal (see RFC7541§7.1.3 for more details).

The following equations should hold:

• get (add t name value) name = Some value

add_unless_exists t ?sensitive name value is a collection of header fields that is the same as t if t already inclues name, and otherwise is equivalent to add t ?sensitive name value.

add_list t assoc is a collection of header fields that is the same as t except with all the header fields in assoc added to the end of the transmission order, in reverse order.

add_multi t assoc is the same as

  add_list
    t
    (List.concat_map assoc ~f:(fun (name, values) ->
       List.map values ~f:(fun value -> name, value)))

but is implemented more efficiently. For example,

  add_multi t [ "name1", [ "x", "y" ]; "name2", [ "p", "q" ] ]
  = add_list [ "name1", "x"; "name1", "y"; "name2", "p"; "name2", "q" ]

remove t name is a collection of header fields that contains all the header fields of t except those that have a header-field name that are equal to name. If t contains multiple header fields whose name is name, they will all be removed.

replace t ?sensitive name value is a collection of header fields that is the same as t except with all header fields with a name equal to name removed and replaced with a single header field whose name is name and whose value is value. This new header field will appear in the transmission order where the first occurrence of a header field with a name matching name was found.

If no header field with a name equal to name is present in t, then the result is simply t, unchanged.

mem t name is true iff t includes a header field with a name that is equal to name.

get t name returns the last header from t with name name, or None if no such header is present.

get t name returns the last header from t with name name, or raises if no such header is present.

get_multi t name is the list of header values in t whose names are equal to name. The returned list is in transmission order.