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Verbatim includes and templates

It is sometimes convenient to put some text in external file. HereDoc extends the syntax to provides four kind of includes: verbatim, templates, declaration includes and expression includes.

  1. VERBATIM "file.txt" returns a string with the content of the given file.
  2. TPL "file.txt" returns the content of the file, interpreted as a quotation (of type Text.t).
  3. INCLUDE "file.txt" (at the position of a toplevel declaration or of a structure implementation item) includes the content of the file.
  4. EXPR "file.txt" same as INCLUDE, but for an expression.

To print a template, use:

Text.iter print_string TPL "file.txt"

You can put several chunks of text in a file. Use the notation:


to designate the section "chunk" in the file "file.txt", that is all the lines between the line "==chunk==" (two signs equal, the name of the chunk, two signs equal, alone on their line), and the line "====" (four signs equal).

Templates and expression includes may take arguments: if the opening ligne is ==chunk arg1 arg2 .. argn== instead of ==chunk==, the chunk returns a function with labeled arguments arg1,...,argn. For instance, if the template file is:

 ==add x y==
 x + y

 ==link dest txt==
 <a href="$dest">$txt</a>

you can declare:

let add = EXPR "file.txt"."add"
let link = TPL "file.txt"."link"

and get:

val add : x:int -> y:int -> int
val link : dest:'a -> txt:'b -> Text.t

If many of the chunks you need are in the same file, you can use the toplevel phrase:

TEMPLATE_FILE "file.txt"

and then omit the file name, for instance:

TPL ."chunck"

When parsing an external template, the default file is the current file. By default, the template filename is "templates.tpl".

The commands "VERBATIM", "EXPR" and "TPL" are expressions; you can use them inside "expression in quotation". So you can for instance include a template from a template :

 Want to see another template ?
 $$TPL ."another"$$

Author's mail : Alain.Frisch@ens.fr Author homepage: http://www.eleves.ens.fr:8080/home/frisch

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