lucid

Clear to write, read and edit DSL for writing HTML

Introduction

HTML terms in Lucid are written with a postfix ‘_’ to indicate data rather than code. Some examples:

p_, class_, table_, style_

See Lucid.Html5 for a complete list of Html5 combinators.

Plain text is written using the OverloadedStrings and ExtendedDefaultRules extensions, and is automatically escaped:

λ> "123 < 456" :: Html ()

123 < 456

Elements nest by function application:

λ> table_ (tr_ (td_ (p_ "Hello, World!")))

<table><tr><td><p>Hello, World!</p></td></tr></table>

Elements are juxtaposed via monoidal append:

λ> p_ "hello" <> p_ "sup"

<p>hello</p><p>sup</p>

Or monadic sequencing:

λ> div_ (do p_ "hello"; p_ "sup")

<div><p>hello</p><p>sup</p></div>

Attributes are set using the 'with' combinator:

λ> with p_ [class_ "brand"] "Lucid Inc"

<p class="brand">Lucid Inc</p>

Here is a fuller example of Lucid:

with table_ [rows_ "2"]
     (tr_ (do with td_ [class_ "top",colspan_ "2"]
                   (p_ "Hello, attributes!")
              td_ "yay!"))

<table rows="2">
  <tr>
     <td class="top" colspan="2">
       <p>Hello, attributes!</p>
     </td>
     <td>yay!</td>
  </tr>
</table>

Rendering

For proper rendering you can easily run some HTML immediately with:

λ> renderText (p_ "Hello!")

"<p>Hello!</p>"

Or to bytes:

λ> renderBS (with p_ [style_ "color:red"] "Hello!")

"<p style=\"color:red\">Hello!</p>"

For ease of use in GHCi, there is a Show instance, as demonstrated above.

If the above rendering functions aren't suited for your purpose, you can run the monad directly via execHtml and use the more low-level blaze Builder, which has a plethora of output modes in Blaze.ByteString.Builder.

See the documentation for the Lucid module for information about using it as a monad transformer.