Text.Blaze

BlazeHtml is an HTML combinator library. It provides a way to embed HTML in Haskell in an efficient and convenient way, with a light-weight syntax.

To use the library, one needs to import a set of HTML combinators. For example, you can use HTML 4 Strict.

 {-# LANGUAGE OverloadedStrings #-}
 import Prelude hiding (head, id, div)
 import Text.Blaze.Html4.Strict hiding (map)
 import Text.Blaze.Html4.Strict.Attributes hiding (title)

To render the page later on, you need a so called Renderer. The recommended renderer is an UTF-8 renderer which produces a lazy bytestring.

 import Text.Blaze.Renderer.Utf8 (renderHtml)

Now, you can describe pages using the imported combinators.

 page1 :: Html
 page1 = html $ do
 	head $ do
		title "Introduction page."
		link ! rel "stylesheet" ! type_ "text/css" ! href "screen.css"
	body $ do
 		div ! id "header" $ "Syntax"
 		p "This is an example of BlazeHtml syntax."
		ul $ forM_ [1, 2, 3] (li . string . show)

The resulting HTML can now be extracted using:

 renderHtml page1

Important types.

type Html = HtmlM ()

Simplification of the HtmlM datatype.

data Tag

Type for an HTML tag. This can be seen as an internal string type used by BlazeHtml.

Instances

IsString Tag

data Attribute

Type for an attribute.

data AttributeValue

The type for the value part of an attribute.

Instances

IsString AttributeValue

Monoid AttributeValue

Creating attributes.

dataAttribute

Arguments

:: Tag

Name of the attribute.

-> AttributeValue

Value for the attribute.

-> Attribute

Resulting HTML attribute.

From HTML 5 onwards, the user is able to specify custom data attributes.

An example:

 <p data-foo="bar">Hello.</p>

We support this in BlazeHtml using this funcion. The above fragment could be described using BlazeHtml with:

 p ! dataAttribute "foo" "bar" $ "Hello."

customAttribute

Arguments

:: Tag

Name of the attribute

-> AttributeValue

Value for the attribute

-> Attribute

Resulting HTML attribtue

Create a custom attribute. This is not specified in the HTML spec, but some JavaScript libraries rely on it.

An example:

 <select dojoType="select">foo</select>

Can be produced using:

 select ! customAttribute "dojoType" "select" $ "foo"

Converting values to HTML.

text

Arguments

:: Text

Text to render.

-> Html

Resulting HTML fragment.

Render text. Functions like these can be used to supply content in HTML.

preEscapedText

Arguments

:: Text

Text to insert.

-> Html

Render text without escaping.

string

Arguments

:: String

String to insert.

-> Html

Resulting HTML fragment.

Create an HTML snippet from a String.

preEscapedString

Arguments

:: String

String to insert.

-> Html

Resulting HTML fragment.

Create an HTML snippet from a String without escaping

showHtml

Arguments

:: Show a

=> a

Value to insert.

-> Html

Resulting HTML fragment.

Create an HTML snippet from a datatype that instantiates Show.

preEscapedShowHtml

Arguments

:: Show a

=> a

Value to insert.

-> Html

Resulting HTML fragment.

Create an HTML snippet from a datatype that instantiates Show. This function will not do any HTML entity escaping.

unsafeByteString

Arguments

:: ByteString

Value to insert.

-> Html

Resulting HTML fragment.

Insert a ByteString. This is an unsafe operation:

• The ByteString could have the wrong encoding.
• The ByteString might contain illegal HTML characters (no escaping is done).

Creating tags.

textTag

Arguments

:: Text

Text to create a tag from

-> Tag

Resulting tag

Create a Tag from some Text.

stringTag

Arguments

:: String

String to create a tag from

-> Tag

Resulting tag

Create a Tag from a String.

Converting values to attribute values.

textValue

Arguments

:: Text

The actual value.

-> AttributeValue

Resulting attribute value.

Render an attribute value from Text.

preEscapedTextValue

Arguments

:: Text

Text to insert.

-> AttributeValue

Render an attribute value from Text without escaping.

stringValue :: String -> AttributeValue

Create an attribute value from a String.

preEscapedStringValue :: String -> AttributeValue

Create an attribute value from a String without escaping.

unsafeByteStringValue

Arguments

:: ByteString

ByteString value

-> AttributeValue

Resulting attribute value

Create an attribute value from a ByteString. See unsafeByteString for reasons why this might not be a good idea.

Setting attributes

(!) :: Attributable h => h -> Attribute -> h

Apply an attribute to an element.

Example:

 img ! src "foo.png"

Result:

 <img src="foo.png" />

This can be used on nested elements as well.

Example:

 p ! style "float: right" $ "Hello!"

Result:

 <p style="float: right">Hello!</p>