Module HTML.Base

defaultEncoding :: String   

The default encoding used in generated web pages.

Further infos:

• solution complete, i.e., able to compute all solutions

idOfCgiRef :: CgiRef -> String   

Internal identifier of a CgiRef (intended only for internal use in other libraries!).

Further infos:

• solution complete, i.e., able to compute all solutions

textOf :: [HtmlExp] -> String   

Extracts the textual contents of a list of HTML expressions. For instance,

textOf [HtmlText "xy", HtmlStruct "a" [] [HtmlText "bc"]] == "xy bc"

formDefWithID :: String -> IO a -> (a -> [HtmlExp]) -> HtmlFormDef a   

A definition of a form with a unique identifier of form (usually, the qualified name of the operation defining the form). A form contains a (reading!) IO action and a mapping from data into an HTML expression (which usually contains event handlers to produce the form answers). It is assumed that the IO action reads only data and does not change it, since it is applied twice when executing a form.

Further infos:

• solution complete, i.e., able to compute all solutions

formDefId :: HtmlFormDef a -> String   

Returns the identifier of a form definition.

Further infos:

• solution complete, i.e., able to compute all solutions

instCgiRefs :: [HtmlExp] -> Int -> ([HtmlExp],Int)   

Instantiates all CgiRefs with a unique tag in HTML expressions. Only internally used.

Further infos:

• partially defined

pageEnc :: String -> PageParam   

An encoding scheme for a HTML page.

Further infos:

• solution complete, i.e., able to compute all solutions

pageCookie :: (String,String) -> PageParam   

A cookie to be sent to the client's browser when a HTML page is requested.

Further infos:

• solution complete, i.e., able to compute all solutions

pageCSS :: String -> PageParam   

A URL for a CSS file for a HTML page.

Further infos:

• solution complete, i.e., able to compute all solutions

pageMetaInfo :: [(String,String)] -> PageParam   

Meta information for a HTML page. The argument is a list of attributes included in the meta-tag in the header for this page.

Further infos:

• solution complete, i.e., able to compute all solutions

pageLinkInfo :: [(String,String)] -> PageParam   

Link information for a HTML page. The argument is a list of attributes included in the link-tag in the header for this page.

Further infos:

• solution complete, i.e., able to compute all solutions

pageBodyAttr :: (String,String) -> PageParam   

Optional attribute for the body element of the web page. More than one occurrence is allowed, i.e., all such attributes are collected.

Further infos:

• solution complete, i.e., able to compute all solutions

page :: String -> [HtmlExp] -> HtmlPage   

A basic HTML web page with the default encoding.

Example call:

(page title hexps)

Parameters:

• title : the title of the page
• hexps : the page's body (list of HTML expressions)

Returns:

an HTML page

Further infos:

• solution complete, i.e., able to compute all solutions

standardPage :: String -> [HtmlExp] -> HtmlPage   

A standard HTML web page where the title is included in the body as the first header.

Example call:

(standardPage title hexps)

Parameters:

• title : the title of the page
• hexps : the page's body (list of HTML expressions)

Returns:

an HTML page with the title as the first header

addPageParam :: HtmlPage -> PageParam -> HtmlPage   

Adds a parameter to an HTML page.

Example call:

(addPageParam page param)

Parameters:

• page : a page
• param : a page's parameter

Returns:

an HTML page

Further infos:

• defined as left-associative infix operator with precedence 0
• solution complete, i.e., able to compute all solutions

addCookies :: [(String,String)] -> HtmlPage -> HtmlPage   

Add simple cookie to an HTML page. The cookies are sent to the client's browser together with this page.

Example call:

(addCookies cs form)

Parameters:

• cs : the cookies as a list of name/value pairs
• form : the form to add cookies to

Returns:

a new HTML page

addHttpHeader :: String -> String -> HtmlPage -> HtmlPage   

Add a HTTP header to a HTML page. Headers are sent to the client's browser together with the page.

Example call:

(addHttpHeader key value page)

Parameters:

• key : the name of the HTTP header field
• value : the value of the HTTP header field
• page : the page to which the header is added

Returns:

a new HTML page

formatCookie :: (String,String,[CookieParam]) -> String   

answerText :: String -> HtmlPage   

A textual result instead of an HTML page as a result for active web pages.

Example call:

(answerText txt)

Parameters:

• txt : the contents of the result page

Returns:

an HTML answer page

Further infos:

• solution complete, i.e., able to compute all solutions

answerEncText :: String -> String -> HtmlPage   

A textual result instead of an HTML page as a result for active web pages where the encoding is given as the first parameter.

Example call:

(answerEncText enc txt)

Parameters:

• enc : the encoding of the text(e.g., "utf-8" or "iso-8859-1")
• txt : the contents of the result page

Returns:

an HTML answer page

Further infos:

• solution complete, i.e., able to compute all solutions

redirectPage :: String -> HtmlPage   

Generates a redirection page to a given URL. This is implemented via the HTTP response header Location (see also https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Location).

Example call:

(redirectPage url page)

Parameters:

• url : The URL target of the redirection
• page : The redirection page

expires :: Int -> HtmlPage -> HtmlPage   

Adds expire time to given HTML page.

Example call:

(expires secs page)

Parameters:

• secs : Number of seconds before document expires
• page : The page to add the header information to

htxt :: String -> HtmlExp   

Basic text as HTML expression. The text may contain special HTML chars (like <,>,&,") which will be quoted so that they appear as in the parameter string.

htxts :: [String] -> [HtmlExp]   

A list of strings represented as a list of HTML expressions. The strings may contain special HTML chars that will be quoted.

hempty :: HtmlExp   

An empty HTML expression.

Further infos:

• solution complete, i.e., able to compute all solutions

nbsp :: HtmlExp   

Non breaking Space

Further infos:

• solution complete, i.e., able to compute all solutions

h1 :: [HtmlExp] -> HtmlExp   

Header 1

Further infos:

• solution complete, i.e., able to compute all solutions

h2 :: [HtmlExp] -> HtmlExp   

Header 2

Further infos:

• solution complete, i.e., able to compute all solutions

h3 :: [HtmlExp] -> HtmlExp   

Header 3

Further infos:

• solution complete, i.e., able to compute all solutions

h4 :: [HtmlExp] -> HtmlExp   

Header 4

Further infos:

• solution complete, i.e., able to compute all solutions

h5 :: [HtmlExp] -> HtmlExp   

Header 5

Further infos:

• solution complete, i.e., able to compute all solutions

h6 :: [HtmlExp] -> HtmlExp   

Header 6

Further infos:

• solution complete, i.e., able to compute all solutions

par :: [HtmlExp] -> HtmlExp   

Paragraph

Further infos:

• solution complete, i.e., able to compute all solutions

section :: [HtmlExp] -> HtmlExp   

Section

Further infos:

• solution complete, i.e., able to compute all solutions

header :: [HtmlExp] -> HtmlExp   

Header

Further infos:

• solution complete, i.e., able to compute all solutions

footer :: [HtmlExp] -> HtmlExp   

Footer

Further infos:

• solution complete, i.e., able to compute all solutions

emphasize :: [HtmlExp] -> HtmlExp   

Emphasize

Further infos:

• solution complete, i.e., able to compute all solutions

strong :: [HtmlExp] -> HtmlExp   

Strong (more emphasized) text.

Further infos:

• solution complete, i.e., able to compute all solutions

bold :: [HtmlExp] -> HtmlExp   

Boldface

Further infos:

• solution complete, i.e., able to compute all solutions

italic :: [HtmlExp] -> HtmlExp   

Italic

Further infos:

• solution complete, i.e., able to compute all solutions

nav :: [HtmlExp] -> HtmlExp   

Navigation

Further infos:

• solution complete, i.e., able to compute all solutions

code :: [HtmlExp] -> HtmlExp   

Program code

Further infos:

• solution complete, i.e., able to compute all solutions

center :: [HtmlExp] -> HtmlExp   

Centered text

Further infos:

• solution complete, i.e., able to compute all solutions

blink :: [HtmlExp] -> HtmlExp   

Blinking text

Further infos:

• solution complete, i.e., able to compute all solutions

teletype :: [HtmlExp] -> HtmlExp   

Teletype font

Further infos:

• solution complete, i.e., able to compute all solutions

pre :: [HtmlExp] -> HtmlExp   

Unformatted input, i.e., keep spaces and line breaks and don't quote special characters.

Further infos:

• solution complete, i.e., able to compute all solutions

verbatim :: String -> HtmlExp   

Verbatim (unformatted), special characters (<,>,&,") are quoted.

address :: [HtmlExp] -> HtmlExp   

Address

Further infos:

• solution complete, i.e., able to compute all solutions

href :: String -> [HtmlExp] -> HtmlExp   

Hypertext reference

Further infos:

• solution complete, i.e., able to compute all solutions

anchor :: String -> [HtmlExp] -> HtmlExp   

An anchored text with a hypertext reference inside a document.

Further infos:

• solution complete, i.e., able to compute all solutions

ulist :: [[HtmlExp]] -> HtmlExp   

Unordered list.

Example call:

(ulist items)

Parameters:

• items : the list items where each item is a list of HTML expressions

ulistWithClass :: String -> String -> [[HtmlExp]] -> HtmlExp   

An unordered list with classes for the entire list and the list elements. The class annotation will be ignored if it is empty.

Example call:

(ulistWithClass listclass itemclass items)

Parameters:

• listclass : the class for the entire list structure
• itemclass : the class for the list items
• items : the list items where each item is a list of HTML expressions

ulistWithItemClass :: String -> [(String,[HtmlExp])] -> HtmlExp   

An unordered list with classes for the entire list individual classes for the list elements. The class annotation will be ignored if it is empty.

Example call:

(ulistWithItemClass listclass classitems)

Parameters:

• listclass : the class for the entire list structure
• classitems : the list items together with their classes

olist :: [[HtmlExp]] -> HtmlExp   

Ordered list.

Example call:

(olist items)

Parameters:

• items : the list items where each item is a list of HTML expressions

olistWithClass :: String -> String -> [[HtmlExp]] -> HtmlExp   

An ordered list with classes for the entire list and the list elements. The class annotation will be ignored if it is empty.

Example call:

(olistWithClass listclass itemclass items)

Parameters:

• listclass : the class for the entire list structure
• itemclass : the class for the list items
• items : the list items where each item is a list of HTML expressions

olistWithItemClass :: String -> [(String,[HtmlExp])] -> HtmlExp   

An ordered list with classes for the entire list individual classes for the list elements. The class annotation will be ignored if it is empty.

Example call:

(olistWithItemClass listclass classitems)

Parameters:

• listclass : the class for the entire list structure
• classitems : the list items together with their classes

litem :: [HtmlExp] -> HtmlExp   

A single list item (usually not explicitly used)

Further infos:

• solution complete, i.e., able to compute all solutions

dlist :: [([HtmlExp],[HtmlExp])] -> HtmlExp   

Description list

Example call:

(dlist items)

Parameters:

• items : a list of (title/description) pairs (of HTML expressions)

table :: [[[HtmlExp]]] -> HtmlExp   

Table with a matrix of items where each item is a list of HTML expressions.

tableWithClass :: String -> String -> String -> [[[HtmlExp]]] -> HtmlExp   

Table with a matrix of items (each item is a list of HTML expressions) with classes for the entire table, each row, and each data element. The class annotation will be ignored if it is empty.

Example call:

(tableWithClass tableclass rowclass dataclass items)

Parameters:

• tableclass : the class for the entire table structure
• rowclass : the class for the table rows
• dataclass : the class for the table data items
• items : the matrix of table items where each item is a list of HTML expressions

headedTable :: [[[HtmlExp]]] -> HtmlExp   

Similar to table but introduces header tags for the first row.

addHeadings :: HtmlExp -> [[HtmlExp]] -> HtmlExp   

Add a row of items (where each item is a list of HTML expressions) as headings to a table. If the first argument is not a table, the headings are ignored.

hrule :: HtmlExp   

Horizontal rule

Further infos:

• solution complete, i.e., able to compute all solutions

breakline :: HtmlExp   

Break a line

Further infos:

• solution complete, i.e., able to compute all solutions

image :: String -> String -> HtmlExp   

Image

Example call:

(image src alt)

Parameters:

• src : the URL of the image
• alt : the alternative text shown instead of the image

styleSheet :: String -> HtmlExp   

Defines a style sheet to be used in this HTML document.

Example call:

(styleSheet css)

Parameters:

• css : a string in CSS format

Further infos:

• solution complete, i.e., able to compute all solutions

style :: String -> [HtmlExp] -> HtmlExp   

Provides a style for HTML elements. The style argument is the name of a style class defined in a style definition (see styleSheet) or in an external style sheet (see form and page parameters FormCSS and PageCSS).

Example call:

(style st hexps)

Parameters:

• st : name of a style class
• hexps : list of HTML expressions

Further infos:

• solution complete, i.e., able to compute all solutions

textstyle :: String -> String -> HtmlExp   

Provides a style for a basic text. The style argument is the name of a style class defined in an external style sheet.

Example call:

(textstyle st txt)

Parameters:

• st : name of a style class
• txt : a string (special characters will be quoted)

blockstyle :: String -> [HtmlExp] -> HtmlExp   

Provides a style for a block of HTML elements. The style argument is the name of a style class defined in an external style sheet. This element is used (in contrast to "style") for larger blocks of HTML elements since a line break is placed before and after these elements.

Example call:

(blockstyle st hexps)

Parameters:

• st : name of a style class
• hexps : list of HTML expressions

Further infos:

• solution complete, i.e., able to compute all solutions

inline :: [HtmlExp] -> HtmlExp   

Joins a list of HTML elements into a single HTML element. Although this construction has no rendering, it is sometimes useful for programming when several HTML elements must be put together.

Example call:

(inline hexps)

Parameters:

• hexps : list of HTML expressions

Further infos:

• solution complete, i.e., able to compute all solutions

block :: [HtmlExp] -> HtmlExp   

Joins a list of HTML elements into a block. A line break is placed before and after these elements.

Example call:

(block hexps)

Parameters:

• hexps : list of HTML expressions

Further infos:

• solution complete, i.e., able to compute all solutions

formExp :: HtmlFormDef a -> HtmlExp   

A form embedded in an HTML expression. The parameter is a form defined as an exported top-level operation in the CGI program so that it can be accessed by the main program. The URL of the generated form is the same as the main page, i.e., the current URL parameter is passed to the form (which is useful for REST-based programming with URL parameters). The form uses a hidden field named FORMID to identify the form in the submitted form controller.

button :: String -> ((CgiRef -> String) -> IO HtmlPage) -> HtmlExp   

A button to submit a form with a label string and an event handler.

resetButton :: String -> HtmlExp   

Reset button with a label string

imageButton :: String -> ((CgiRef -> String) -> IO HtmlPage) -> HtmlExp   

Submit button in form of an imag.

Example call:

(imageButton src handler)

Parameters:

• src : url of the image
• handler : event handler

textField :: CgiRef -> String -> HtmlExp   

Input text field with a reference and an initial contents

password :: CgiRef -> HtmlExp   

Input text field (where the entered text is obscured) with a reference

textArea :: CgiRef -> (Int,Int) -> String -> HtmlExp   

Input text area with a reference, height/width, and initial contents

checkBox :: CgiRef -> String -> HtmlExp   

A checkbox with a reference and a value. The value is returned if checkbox is on, otherwise "" is returned.

checkedBox :: CgiRef -> String -> HtmlExp   

A checkbox that is initially checked with a reference and a value. The value is returned if checkbox is on, otherwise "" is returned.

radioMain :: CgiRef -> String -> HtmlExp   

A main button of a radio (initially "on") with a reference and a value. The value is returned of this button is on. A complete radio button suite always consists of a main button (radiomain) and some further buttons (radioothers) with the same reference. Initially, the main button is selected (or nothing is selected if one uses radiomainoff instead of radio_main). The user can select another button but always at most one button of the radio can be selected. The value corresponding to the selected button is returned in the environment for this radio reference.

radioMainOff :: CgiRef -> String -> HtmlExp   

A main button of a radio (initially "off") with a reference and a value. The value is returned of this button is on.

radioOther :: CgiRef -> String -> HtmlExp   

A further button of a radio (initially "off") with a reference (identical to the main button of this radio) and a value. The value is returned of this button is on.

selection :: CgiRef -> [(String,String)] -> HtmlExp   

A selection button with a reference and a list of name/value pairs. The names are shown in the selection and the value is returned for the selected name.

selectionInitial :: CgiRef -> [(String,String)] -> Int -> HtmlExp   

A selection button with a reference, a list of name/value pairs, and a preselected item in this list. The names are shown in the selection and the value is returned for the selected name.

Example call:

(selectionInitial ref nvs sel)

Parameters:

• ref : a CGI reference
• nvs : list of name/value pairs
• sel : the index of the initially selected item in the list nvs

Returns:

an HTML expression representing the selection button

multipleSelection :: CgiRef -> [(String,String,Bool)] -> HtmlExp   

A selection button with a reference and a list of name/value/flag pairs. The names are shown in the selection and the value is returned if the corresponding name is selected. If flag is True, the corresonding name is initially selected. If more than one name has been selected, all values are returned in one string where the values are separated by newline (<code><a href="#\n">\n</a></code>) characters.

hiddenField :: String -> String -> HtmlExp   

A hidden field to pass a value referenced by a fixed name. This function should be used with care since it may cause conflicts with the CGI-based implementation of this library.

Further infos:

• solution complete, i.e., able to compute all solutions

htmlQuote :: String -> String   

Quotes special characters (<,>,&,", umlauts) in a string as HTML special characters.

htmlIsoUmlauts :: String -> String   

Translates umlauts in iso-8859-1 encoding into HTML special characters.

addAttr :: HtmlExp -> (String,String) -> HtmlExp   

Adds an attribute (name/value pair) to an HTML element.

Further infos:

• defined as left-associative infix operator with precedence 0
• solution complete, i.e., able to compute all solutions

addAttrs :: HtmlExp -> [(String,String)] -> HtmlExp   

Adds a list of attributes (name/value pair) to an HTML element.

Further infos:

• defined as left-associative infix operator with precedence 0
• solution complete, i.e., able to compute all solutions

addClass :: HtmlExp -> String -> HtmlExp   

Adds a class attribute to an HTML element (if the class attribute is not empty).

Further infos:

• defined as left-associative infix operator with precedence 0

showHtmlExps :: [HtmlExp] -> String   

Transforms a list of HTML expressions into string representation.

showHtmlExp :: HtmlExp -> String   

Transforms a single HTML expression into string representation.

showHtmlPage :: HtmlPage -> String   

Transforms HTML page into string representation.

Example call:

(showHtmlPage page)

Parameters:

• page : the HTML page

Returns:

string representation of the HTML document

htmlPrelude :: String   

Standard header for generated HTML pages.

Further infos:

• solution complete, i.e., able to compute all solutions

htmlTagAttrs :: [(String,String)]   

Standard attributes for element "html".

Further infos:

• solution complete, i.e., able to compute all solutions

getUrlParameter :: IO String   

Gets the parameter attached to the URL of the script. For instance, if the script is called with URL "http://.../script.cgi?parameter", then "parameter" is returned by this I/O action. Note that an URL parameter should be "URL encoded" to avoid the appearance of characters with a special meaning. Use the functions "urlencoded2string" and "string2urlencoded" to decode and encode such parameters, respectively.

urlencoded2string :: String -> String   

Translates urlencoded string into equivalent ASCII string.

string2urlencoded :: String -> String   

Translates arbitrary strings into equivalent urlencoded string.

getCookies :: IO [(String,String)]   

Gets the cookies sent from the browser for the current CGI script. The cookies are represented in the form of name/value pairs since no other components are important here.

coordinates :: (CgiRef -> String) -> Maybe (Int,Int)   

For image buttons: retrieve the coordinates where the user clicked within the image.