html_dcg_example.pl

:- use_module(library(http/thread_httpd)).
:- use_module(library(http/http_dispatch)).
:- use_module(library(http/http_error)).
:- use_module(library(http/html_write)).

% Declare a handler, binding an HTTP path to a predicate.
% Here our path is / (the root) and the goal we'll query will be
% say_hi. The third argument is for options
:- http_handler('/', say_hi, []).

% The predicate server(+Port) starts the server. It simply creates a
% number of Prolog threads and then returns to the toplevel, so you can
% (re-)load code, debug, etc.
server(Port) :-
  http_server(http_dispatch, [port(Port)]).

/* The implementation of /. The single argument provides the request
details, which we ignore for now. Our task is to write a CGI-Document:
a number of name: value -pair lines, followed by two newlines, followed
by the document content, The only obligatory header line is the
Content-type: <mime-type> header.
Printing is done with print_html, which takes a list of tokens and
prints them. It attempts to 'reasonably' format html when it recognizes
tags. */

say_hi(_Request) :-
	phrase(
	  html([
			head(title('Howdy')),
		 	body([
				h1('A Simple Web Page'),
				p('With some text')
			])
		]),
	TokenizedHtml,
	[]),
	format('Content-type: text/html~n~n'),
	print_html(TokenizedHtml).