In this section we will be concerned with generation of one of more HTML pages from a LAML source document. Let us start with a simple example. We wish to make a web page that display the first few factorial numbers:
1!, 2!, 3!, ...,
Please take a look at the fac-1 page (click on the red name to see the program) which corresponds directly to the fac-1 document in the 'getting started' examples. You should also take a look at the page which is generated by the program.
The first line loads "laml.scm" from your LAML installation. The value of laml-dir is transferred from the context (by a shell script, by Emacs, or by other means) and it is bound at LAML installation time. The value of laml-dir is the directory path to your LAML installation.
The second line uses a LAML style simple-xhtml1.0-transitional-validating. In this case we are using a style that allows us to use the XHTML1.0 transitional mirror functions. The use of this style takes responsibility to load the relevant libraries. As we will see later, other LAML styles are more substantial, in the sense that they offer more than just function that supports HTML counterparts. Such more substantial document styles typically generate HTML contents based on high level specifications at the level of XML.
Following that we activate begin-laml which marks ending of the loading part, and the beginning of the real document part of the program.
Next follows the recursive factorial function fac. This is the usual factorial function, which you probably have seen many times before.
The middle big part of the example shows a call to write-xml. (You can click on the name to see its SchemeDoc interface documentation). The write-xml procedure comes from the laml.scm library, and it renders and writes a HTML fragment onto some file. If no file name is passed, it writes the file on fac-1.html, because the proper source name of the example is fac-1. This is a common behavior of many LAML programs/documents. The first parameter '(raw prolog) is a list of properties; Here we ask for raw writing of the HTML fragment. We also ask for the generation of a document prolog (document type definition). Alternatively we could, for instance, pass '(pp prolog epilog) which asks for HTML pretty printing, document prolog (as given by the function standard-prolog ), and document epilog (as given by the function standard-epilog ).
The expression
(html
(head
(title "Factorials"))
(body
(h1 "Factorials")
(table 'border "1"
(tbody
(tr
(td "1") (td (fac 1)))
(tr
(td "2") (td (fac 2)))
(tr
(td "3") (td (fac 3)))
(tr
(td "4") (td (fac 4)))))
))
uses quite a few of the so-called mirror functions: html, head, body, h1, table, tbody, tr, and td. These functions correspond directly to the elements (tags) of HTML. The expression is evaluated to some internal structure (not shown in full)
(ast "html"
((ast "head"
((ast "title" ("Factorials") () double)) () double) ... )
() double)
which can be rendered (linearized to normal HTML text) as
<html>
<head><title>Factorials</title></head>
<body><h1>Factorials</h1>
<table border = "1">
<tbody>
<tr><td>1</td> <td>1</td></tr>
<tr><td>2</td> <td>2</td></tr>
<tr><td>3</td> <td>6</td></tr>
<tr><td>4</td> <td>24</td></tr>
</tbody>
</table>
</body>
</html>
In the context of our example, fac-1, the function write-xml will do the rendering.
Notice that the numbers returned by (fac 1), (fac 2), (fac 3), and (fac 4) are automatically converted to text strings by the mirror functions.
Finally, the expression (end-laml) says goodbye in a gentle way, and it reports about time consumption. The procedure end-laml initiates the final part of the document validation, and it is able to check the links in the document).
We process the LAML document by simply running it as a Scheme program. As mentioned, a tiny bit of contextual information is passed to the Scheme interpreter: laml-dir, the name of the source file (source-filename-without-extension), and the directory in which the file is located (startup-directory).
The best and the easiest way to process the document is from Emacs, where the Emacs LAML mode binds the C-c C-o (Control c followed by Control o) key to an Emacs command laml-process-current-buffer that activates your Scheme interpreter. LAML mode in Emacs also offers a menu with a number of useful commands. Try it out on the files in the example directory!
You can also, from Emacs, activate M-x run-laml-interactively and then issue the command
(laml "fac-1")
You also find run-laml-interactively in the Tools > Laml menu of Emacs.
You can also just start your Scheme system, define laml-dir and the contextual information, and then load the laml program by (load "fac-1.laml"). See additional details on this mode of activation.
Finally, you can activate LAML from a command prompt (shell) in both Windows and Unix. Locate yourself in the appropriate directory and say
> laml fac-1.laml
The prefix > denotes the prompt, so do not write that part yourself! Consult the laml (or laml.exe ) command in the bin directory of your local LAML directory, and make sure that it is executable (in Unix), and that the bin directory of your LAML system is in your path.
