This package contains libraries to support HTML programming. It provides a similar API as package
html. In contrast to package
html, this library implements dynamic web pages without server processes waiting for answers form the client (web browser). Thus, it does not need the Curry Port Name Server (CPNS), the HTML/CGI Registry, etc. For this purpose, web forms are a bit more restricted: each web form has an IO action to read the data required for the form and a result page shown after submitting the form. To implement the event handlers inside a form without a process, the read IO action is executed again when a form is submitted.
All operations and smart constructors to implement interactive web pages are defined in the library
HTML.Base. A form inside a web page must be defined as a public top-level operation of type
myForm :: HtmlFormDef String myForm = formDefWithID "Module.myForm" readData viewData
The first argument of a form definition must be the qualified name of the operation (this will be checked by the script
curry2cgi which is used to install such web scripts as CGI executables). The second argument is an IO action to read some data used in the form, and the third argument is the actual view of the form which usually contains buttons with event handlers that are invoked when a form is submitted.
For convencience, there is also the form constructor
formDef where the ID argument can be omitted:
myForm :: HtmlFormDef String myForm = formDef readData viewData
If this constructor is used, the script
curry2cgi automatically transforms the intermediate FlatCurry program such that the correct form ID is added.
Some simple examples for dynamic web pages can be found in the directory
The automatic addition of form IDs with the script
curry2cgi does not work completely with KiCS2 due to a problem in the front end which unecessarily re-compiles TypedFlatCurry files used by KiCS2. Thus, it is safer (and more efficient) to use
formDefWithID to define forms.