Module Rss

The RSS library to read and write RSS 2.0 files.

Reference: RSS 2.0 specification.

Types

type category = {
cat_name : string;

A forward-slash-separated string that identifies a hierarchic location in the indicated taxonomy.

cat_domain : Uri.t option;

Identifies a categorization taxonomy.

}
type image = {
image_url : Uri.t;

The URL of a GIF, JPEG or PNG image that represents the channel.

image_title : string;

Description of the image, it's used in the ALT attribute of the HTML <img> tag when the channel is rendered in HTML.

image_height : int option;

Height of the image, in pixels.

image_width : int option;

Width of the image, in pixels.

image_desc : string option;

Text to be included in the "title" attribute of the link formed around the image in the HTML rendering.

}
type text_input = {
ti_title : string;

The label of the Submit button in the text input area.

ti_desc : string;

Explains the text input area.

ti_name : string;

The name of the text object in the text input area.

}
type enclosure = {
encl_url : Uri.t;

URL of the enclosure

encl_length : int;

size in bytes

encl_type : string;

MIME type

}
type guid =
| Guid_name of string

A string that uniquely identifies the item.

type source = {
src_name : string;
src_url : Uri.t;
}
type cloud = {
cloud_domain : string;
cloud_port : int;
cloud_path : string;
cloud_register_procedure : string;
cloud_protocol : string;
}

See specification

type 'a item_t = {
item_title : string option;

Optional title

item_desc : string option;

Optional description

item_pubdate : Ptime.t option;

Date of publication

item_author : string option;

The email address of the author of the item.

item_categories : category list;

Categories for the item. See the field category.

item_comments : Uri.t option;

Url of comments about this item

item_enclosure : enclosure option;
item_guid : guid option;

A globally unique identifier for the item.

item_source : source option;
item_data : 'a option;

Additional data, since RSS can be extended with namespace-prefixed nodes.

}

An item may represent a "story". Its description is a synopsis of the story (or sometimes the full story), and the link points to the full story.

type namespace = string * string

A namespace is a pair (name, url).

type ('a, 'b) channel_t = {
ch_title : string;

Mandatory. The name of the channel, for example the title of your web site.

ch_desc : string;

Mandatory. A sentence describing the channel.

ch_language : string option;

Language of the news, e.g. "en". See the W3C language codes.

ch_managing_editor : string option;

Managing editor of the news.

ch_webmaster : string option;

The address of the webmasterof the site.

ch_pubdate : Ptime.t option;

Publication date of the channel.

ch_last_build_date : Ptime.t option;

When the channel content changed for the last time.

ch_categories : category list;

Categories for the channel. See the field category.

ch_generator : string option;

The tool used to generate this channel.

ch_cloud : cloud option;

Allows processes to register with a cloud to be notified of updates to the channel.

ch_docs : Uri.t option;

An url to a RSS format reference.

ch_ttl : int option;

Time to live, in minutes. It indicates how long a channel can be cached before refreshing from the source.

ch_image : image option;
ch_rating : string option;

The PICS rating for the channel.

ch_text_input : text_input option;
ch_skip_hours : int list option;

A hint for aggregators telling them which hours they can skip.

ch_skip_days : int list option;

A hint for aggregators telling them which days they can skip.

ch_items : 'b item_t list;
ch_data : 'a option;

Additional data, since RSS can be extended with namespace-prefixed nodes.

ch_namespaces : namespace list;
}
type item = unit item_t
type channel = (unit, unit) channel_t

Building items and channels

val item : ?⁠title:string -> ?⁠link:Uri.t -> ?⁠desc:string -> ?⁠pubdate:Ptime.t -> ?⁠author:string -> ?⁠cats:category list -> ?⁠comments:Uri.t -> ?⁠encl:enclosure -> ?⁠guid:guid -> ?⁠source:source -> ?⁠data:'a -> unit -> 'a item_t

item() creates a new item with all fields set to None. Use the optional parameters to set fields.

val channel : title:string -> link:Uri.t -> desc:string -> ?⁠language:string -> ?⁠copyright:string -> ?⁠managing_editor:string -> ?⁠webmaster:string -> ?⁠pubdate:Ptime.t -> ?⁠last_build_date:Ptime.t -> ?⁠cats:category list -> ?⁠generator:string -> ?⁠cloud:cloud -> ?⁠docs:Uri.t -> ?⁠ttl:int -> ?⁠image:image -> ?⁠rating:string -> ?⁠text_input:text_input -> ?⁠skip_hours:int list -> ?⁠skip_days:int list -> ?⁠data:'a -> ?⁠namespaces:namespace list -> 'b item_t list -> ('a'b) channel_t

channel items creates a new channel containing items. Other fields are set to None unless the corresponding optional parameter is used.

val compare_item : ?⁠comp_data:('a -> 'a -> int) -> 'a item_t -> 'a item_t -> int
val copy_item : 'a item_t -> 'a item_t
val copy_channel : ('a'b) channel_t -> ('a'b) channel_t

Manipulating channels

val keep_n_items : int -> ('a'b) channel_t -> ('a'b) channel_t

keep_n_items n ch returns a copy of the channel, keeping only n items maximum.

val sort_items_by_date : 'a item_t list -> 'a item_t list

Sort items by date, older last.

val merge_channels : ('a'b) channel_t -> ('a'b) channel_t -> ('a'b) channel_t

merge_channels c1 c2 merges the given channels in a new channel, sorting items using sort_items_by_date. Channel information are copied from the first channel c1.

Reading channels

type xmltree =
| E of Xmlm.tag * xmltree list
| D of string

This represents XML trees. Such XML trees are given to functions provided to read additional data from RSS channels and items.

val xml_of_source : Xmlm.source -> xmltree

Read an XML tree from a source.

raises Failure

in case of error.

exception Error of string

Use this exception to indicate an error is functions given to make_opts used to read additional data from prefixed XML nodes.

type ('a, 'b) opts

Options used when reading source.

val make_opts : ?⁠read_channel_data:(xmltree list -> 'a option) -> ?⁠read_item_data:(xmltree list -> 'b option) -> unit -> ('a'b) opts
parameter read_channel_data

provides a way to read additional information from the subnodes of the channels. All these subnodes are prefixed by an expanded namespace.

parameter read_item_data

is the equivalent of read_channel_data parameter but is called of each item with its prefixed subnodes.

val default_opts : (unit, unit) opts
val channel_t_of_file : ('a'b) opts -> string -> ('a'b) channel_t * string list

channel_[t_]of_X returns the parsed channel and a list of encountered errors. Note that only namespaces declared in the root not of the XML tree are added to ch_namespaces field.

raises Failure

if the channel could not be parsed.

val channel_t_of_string : ('a'b) opts -> string -> ('a'b) channel_t * string list
val channel_t_of_channel : ('a'b) opts -> Stdlib.in_channel -> ('a'b) channel_t * string list
val channel_t_of_xmls : ('a'b) opts -> xmltree list -> ('a'b) channel_t * string list

Read a channel from XML trees. These trees correspond to nodes under the "channel" XML node of a reguler RSS document.

val channel_of_file : string -> channel * string list
val channel_of_string : string -> channel * string list
val channel_of_channel : Stdlib.in_channel -> channel * string list

Writing channels

type 'a data_printer = 'a -> xmltree list
val print_channel : ?⁠channel_data_printer:'a data_printer -> ?⁠item_data_printer:'b data_printer -> ?⁠indent:int -> ?⁠encoding:string -> Stdlib.Format.formatter -> ('a'b) channel_t -> unit
val print_file : ?⁠channel_data_printer:'a data_printer -> ?⁠item_data_printer:'b data_printer -> ?⁠indent:int -> ?⁠encoding:string -> string -> ('a'b) channel_t -> unit