Module HTML.Base

Exported Datatypes

The attributes for HTML structures consists of a list of name/value pairs.

The data type to represent static HTML expressions in web scripts.

Constructors:

• BaseText :: String -> BaseHtml s - a text string without any further structure
• BaseStruct :: String -> Attrs -> [BaseHtml] -> BaseHtml t as hs - a structure with a tag, attributes, and HTML expressions inside the structure
• BaseAction :: (IO HtmlExp) -> BaseHtml act - an action that computes a general HTML expression which will be inserted when the HTML document is shown (used to implement form expressions)

Known instances:

• HTML BaseHtml

The data type to represent static HTML expressions which can be persistently stored, e.g., read from or written into files. It is similar to type BaseHtml except that there is no constructor BaseAction so this type has instances for standard classes like Eq, Data, Read, and Show.

Constructors:

• HText :: String -> StaticHtml s - a text string without any further structure
• HStruct :: String -> Attrs -> [StaticHtml] -> StaticHtml t as hs - a structure with a tag, attributes, and HTML expressions inside the structure

Known instances:

• HTML StaticHtml
• Eq StaticHtml
• Read StaticHtml
• Show StaticHtml

The (abstract) data type for representing references to input elements in HTML forms.

The type for representing cgi environments, i.e., mappings from cgi references to the corresponding values of the input elements.

The type of event handlers occurring in HTML forms.

The data type for representing HTML expressions with input elements, i.e., all elements which might occur inside a form.

Constructors:

• HtmlText :: String -> HtmlExp s - a text string without any further structure
• HtmlStruct :: String -> Attrs -> [HtmlExp] -> HtmlExp t as hs - a structure with a tag, attributes, and HTML expressions inside the structure
• HtmlAction :: (IO HtmlExp) -> HtmlExp act - an action that computes an HTML expression which will be inserted when the HTML document is shown (used to implement form expressions)
• HtmlInput :: HtmlRef -> HtmlExp -> HtmlExp ref h - an input element (described by the second argument) with a cgi reference
• HtmlEvent :: HtmlRef -> HtmlHandler -> HtmlExp -> HtmlExp h ref hdlr - an input element (first arg) identified by a cgi reference with an associated event handler (typically, a submit button)

Known instances:

• HTML HtmlExp

The type FormReader is a monad with operations to read data to invoke an HTML form. It is assumed that a FormReader action reads only data and does not change the environment, since the action is applied twice when executing a form. A typical action of this kind is HTML.Session.getSessionData.

The FormReader type encapsulates IO actions in order to enforce the correct use of forms.

Known instances:

• Functor FormReader
• Applicative FormReader
• Monad FormReader

The data type for representing HTML forms embedded into HTML pages.

A form definition consists of a unique identifier of form (usually, the qualified name of the operation defining the form), a FormReader action and a mapping from data into an HTML expression (which usually contains event handlers to produce the form answers).

The data type for representing HTML pages. Since the HTML document shown in this page is a base HTML expression, it is ensured that input elements and event handlers occur only in embedded forms.

Constructors:

• HtmlPage :: String -> [PageParam] -> [BaseHtml] -> HtmlPage t ps hs - an HTML page with title t, optional parameters (e.g., cookies) ps, and contents hs
• HtmlAnswer :: String -> String -> HtmlPage t c - an answer in an arbitrary format where t is the content type (e.g., "text/plain") and c is the contents

The possible parameters of an HTML page. The parameters of a cookie (PageCookie) are its name and value and optional parameters (expiration date, domain, path (e.g., the path "/" makes the cookie valid for all documents on the server), security) which are collected in a list.

Constructors:

• PageEnc :: String -> PageParam the encoding scheme of this page
• PageCookie :: String -> String -> [CookieParam] -> PageParam name value params - a cookie to be sent to the client's browser
• PageCSS :: String -> PageParam s - a URL for a CSS file for this page
• HttpHeader :: String -> String -> PageParam key value - additional HTTP header included in this page
• PageJScript :: String -> PageParam s - a URL for a Javascript file for this page
• PageMeta :: [(String, String)] -> PageParam as - meta information (in form of attributes) for this page
• PageLink :: [(String, String)] -> PageParam as - link information (in form of attributes) for this page
• PageHeadInclude :: BaseHtml -> PageParam he - HTML expression to be included in page header
• PageBodyAttr :: (String, String) -> PageParam attr - optional attribute for the body element of the page (more than one occurrence is allowed)

The possible parameters of a cookie.

Constructors:

• CookieExpire :: ClockTime -> CookieParam
• CookieDomain :: String -> CookieParam
• CookiePath :: String -> CookieParam
• CookieSecure :: CookieParam

Exported Functions

defaultEncoding :: String   

The default encoding used in generated HTML documents.

Further infos:

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

htxt :: HTML a => String -> a   

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

htxts :: HTML a => [String] -> [a]   

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

hStruct :: HTML a => String -> [a] -> a   

An HTML structure with a given tag and no attributes.

fromStaticHtml :: HTML a => StaticHtml -> a   

Transforms a StaticHtml expression into a generic HTML expression.

toStaticHtml :: BaseHtml -> StaticHtml   

Transforms a BaseHtml expression into a StaticHtml expression provided that BaseAction constructors do not occur (otherwise, an error is raised).

idOfHtmlRef :: HtmlRef -> String   

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

Further infos:

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

toHtmlExp :: BaseHtml -> HtmlExp   

Transforms a static into a dynamic HTML document.

fromHtmlExp :: HtmlExp -> BaseHtml   

Transforms a dynamic HTML into a static one by dropping references and event handlers.

textOf :: HTML a => [a] -> String   

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

textOf [BaseText "xy", BaseStruct "a" [] [BaseText "bc"]] == "xy bc"

fromFormReader :: FormReader a -> IO a   

Transforms a FormReader action into a standard IO action.

Further infos:

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

toFormReader :: IO a -> FormReader a   

Transforms an IO action into a FormReader action. This operation should be used with care since it must be ensured that the action only reads data and does not change the environment, since the action is applied twice when executing a form.

Further infos:

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

simpleFormDef :: [HtmlExp] -> HtmlFormDef ()   

A definition of a simple form which does not require session data.

The unique identifier required for the implementation of forms is added by the curry2cgi translator.

simpleFormDefWithID :: String -> [HtmlExp] -> HtmlFormDef ()   

A definition of a simple form, which does not require session data, with a unique identifier (usually, the qualified name of the operation defining the form).

formDef :: FormReader a -> (a -> [HtmlExp]) -> HtmlFormDef a   

A definition of a form which consists of a FormReader 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 FormReader action reads only data and does not change it, since it is applied twice when executing a form.

The unique identifier required for the implementation of forms is added by the curry2cgi translator.

Further infos:

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

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

A definition of a form with a unique identifier (usually, the qualified name of the operation defining the form). A form contains a FormReader 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 FormReader 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

setFormDefId :: String -> HtmlFormDef a -> HtmlFormDef a   

Sets the identifier of a form definition. Only intended for internal use in the curry2cgi translator.

Further infos:

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

formDefRead :: HtmlFormDef a -> IO a   

Returns the FormReader action of a form definition.

Further infos:

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

formDefView :: HtmlFormDef a -> a -> [HtmlExp]   

Returns the view operation of a form definition.

Further infos:

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

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

Instantiates all HtmlRefs with a unique tag in HTML expressions. Only internally used. Parameters: HTML expressions, number for cgi-refs Result: translated HTML expressions, new number for cgi-refs

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 -> [BaseHtml] -> HtmlPage   

A basic HTML web page with the default encoding.

Further infos:

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

headerPage :: String -> [BaseHtml] -> HtmlPage   

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

addPageParam :: HtmlPage -> PageParam -> HtmlPage   

Adds a parameter to an HTML page.

Further infos:

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

addPageBody :: HtmlPage -> [BaseHtml] -> HtmlPage   

Adds a list of HTML expressions to the body of an HTML page.

Further infos:

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

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

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

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

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

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

answerText :: String -> HtmlPage   

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

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.

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).

expires :: Int -> HtmlPage -> HtmlPage   

Adds expire time to given HTML page.

hempty :: HTML a => a   

An empty HTML expression.

nbsp :: HTML a => a   

Non breaking Space

h1 :: HTML a => [a] -> a   

Header 1

h2 :: HTML a => [a] -> a   

Header 2

h3 :: HTML a => [a] -> a   

Header 3

h4 :: HTML a => [a] -> a   

Header 4

h5 :: HTML a => [a] -> a   

Header 5

h6 :: HTML a => [a] -> a   

Header 6

par :: HTML a => [a] -> a   

Paragraph

section :: HTML a => [a] -> a   

Section

header :: HTML a => [a] -> a   

Header

footer :: HTML a => [a] -> a   

Footer

emphasize :: HTML a => [a] -> a   

Emphasize

strong :: HTML a => [a] -> a   

Strong (more emphasized) text.

bold :: HTML a => [a] -> a   

Boldface

italic :: HTML a => [a] -> a   

Italic

nav :: HTML a => [a] -> a   

Navigation

code :: HTML a => [a] -> a   

Program code

center :: HTML a => [a] -> a   

Centered text

blink :: HTML a => [a] -> a   

Blinking text

teletype :: HTML a => [a] -> a   

Teletype font

pre :: HTML a => [a] -> a   

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

verbatim :: HTML a => String -> a   

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

address :: HTML a => [a] -> a   

Address

href :: HTML a => String -> [a] -> a   

Hypertext reference

anchor :: HTML a => String -> [a] -> a   

An anchored text with a hypertext reference inside a document.

ulist :: HTML a => [[a]] -> a   

Unordered list.

ulistWithClass :: HTML a => String -> String -> [[a]] -> a   

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

ulistWithItemClass :: HTML a => String -> [(String, [a])] -> a   

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.

olist :: HTML a => [[a]] -> a   

Ordered list.

olistWithClass :: HTML a => String -> String -> [[a]] -> a   

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

olistWithItemClass :: HTML a => String -> [(String, [a])] -> a   

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.

litem :: HTML a => [a] -> a   

A single list item (usually not explicitly used)

dlist :: HTML a => [([a], [a])] -> a   

Description list

table :: HTML a => [[[a]]] -> a   

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

tableWithClass :: HTML a => String -> String -> String -> [[[a]]] -> a   

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.

headedTable :: HTML a => [[[a]]] -> a   

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

hrule :: HTML a => a   

Horizontal rule

breakline :: HTML a => a   

Break a line

image :: HTML a => String -> String -> a   

Image

styleSheet :: HTML a => String -> a   

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

style :: HTML a => String -> [a] -> a   

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).

textstyle :: HTML a => String -> String -> a   

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

blockstyle :: HTML a => String -> [a] -> a   

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.

inline :: HTML a => [a] -> a   

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.

block :: HTML a => [a] -> a   

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

hiddenField :: HTML a => String -> String -> a   

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.

formElem :: HtmlFormDef a -> BaseHtml   

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.

Since form elements can not be nested, see HTML, the form element itself is a static HTML expression.

formElemWithAttrs :: HtmlFormDef a -> [(String, String)] -> BaseHtml   

A form element (see formElem) where some attributes are added to the resulting HTML form structure. The attributes must be different from the standard form attributes method and action.

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

Submit button in form of an imag.

textField :: HtmlRef -> String -> HtmlExp   

Input text field with a reference and an initial contents

password :: HtmlRef -> HtmlExp   

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

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

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

checkBox :: HtmlRef -> String -> HtmlExp   

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

checkedBox :: HtmlRef -> 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 :: HtmlRef -> 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 :: HtmlRef -> 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 :: HtmlRef -> 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 :: HtmlRef -> [(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 :: HtmlRef -> [(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.

multipleSelection :: HtmlRef -> [(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 ([\n](#\n)) characters.

htmlQuote :: String -> String   

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

Further infos:

• partially defined

htmlIsoUmlauts :: String -> String   

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

addAttr :: HTML a => a -> (String, String) -> a   

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

Further infos:

• defined as left-associative infix operator with precedence 0

addAttrs :: HTML a => a -> [(String, String)] -> a   

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

Further infos:

• defined as left-associative infix operator with precedence 0

addClass :: HTML a => a -> String -> a   

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
• partially defined

showStaticHtmls :: [StaticHtml] -> String   

Transforms a list of static HTML expressions into its string representation (in the standard HTML syntax). Only included for compatibility.

showBaseHtmls :: [BaseHtml] -> String   

Transforms a list of basic HTML expressions into its string representation (in the standard HTML syntax). Only included for compatibility.

showHtmls :: HTML a => [a] -> String   

Transforms a list of HTML expressions into its string representation (in the standard HTML syntax).

showHtml :: HTML a => a -> String   

Transforms a single HTML expression into string representation.

showHtmlPage :: HtmlPage -> String   

Transforms HTML page into string representation.

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 urlencoded2string and string2urlencoded from Network.URL to decode and encode such parameters, respectively.

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 :: (HtmlRef -> String) -> Maybe (Int, Int)   

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

Exported Classes

A type is an instance of class HTML if it has operations to construct HTML documents, i.e., constructors for basic text strings and structures with tags and attributes, update the attributes in structures, and selectors for basic text and structures which returns the contents of these elements (or Nothing for different elements).

Methods: