lucid-2.9.8.1: Clear to write, read and edit DSL for HTML

Safe HaskellNone
LanguageHaskell98

Lucid

Contents

Description

Clear to write, read and edit DSL for writing HTML

See Lucid.Html5 for a complete list of Html5 combinators. That module is re-exported from this module for your convenience.

See Lucid.Base for lower level functions like makeElement, makeAttribute, termRaw, etc.

Synopsis

Intro

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

p_, class_, table_, style_

Note: If you're testing in the REPL you need to add a type annotation to indicate that you want HTML. In normal code your top-level declaration signatures handle that.

For GHCi:

:set -XOverloadedStrings -XExtendedDefaultRules@
import Lucid

In a module: {-# LANGUAGE OverloadedStrings, ExtendedDefaultRules #-}

Plain text is written like this, and is automatically escaped:

>>> "123 < 456" :: Html ()
123 &lt; 456

Except some elements, like script_:

>>> script_ "alert('Hello!' > 12)" :: Html ()
<script>alert('Hello!' > 12)</script>

Elements nest by function application:

>>> table_ (tr_ (td_ (p_ "Hello, World!"))) :: Html ()
<table><tr><td><p>Hello, World!</p></td></tr></table>

Elements are juxtaposed via monoidal append (remember to import Data.Monoid):

>>> p_ "hello" <> p_ "sup" :: Html ()
<p>hello</p><p>sup</p>

Or monadic sequencing:

>>> div_ (do p_ "hello"; p_ "sup") :: Html ()
<div><p>hello</p><p>sup</p></div>

Attributes are set by providing an argument list:

>>> p_ [class_ "brand"] "Lucid Inc" :: Html ()
<p class="brand">Lucid Inc</p>
>>> p_ [data_ "zot" "foo",checked_] "Go!" :: Html ()
<p data-zot="foo" checked>go</p>

Attribute and element terms are not conflicting:

>>> style_ [style_ "inception"] "Go deeper." :: Html ()
<style style="inception">Go deeper.</style>

Here is a fuller example of Lucid:

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

Elements (and some attributes) are variadic and overloaded, see the Term class for more explanation about that.

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

>>> renderText (p_ "Hello!")
> "<p>Hello!</p>"
>>> renderBS (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.

renderText :: Html a -> Text Source #

Render the HTML to a lazy Text.

This is a convenience function defined in terms of execHtmlT, runIdentity and toLazyByteString, and decodeUtf8. Check the source if you're interested in the lower-level behaviour.

renderBS :: Html a -> ByteString Source #

Render the HTML to a lazy ByteString.

This is a convenience function defined in terms of execHtmlT, runIdentity and toLazyByteString. Check the source if you're interested in the lower-level behaviour.

renderTextT :: Monad m => HtmlT m a -> m Text Source #

Render the HTML to a lazy Text, but in a monad.

This is a convenience function defined in terms of execHtmlT and toLazyByteString, and decodeUtf8. Check the source if you're interested in the lower-level behaviour.

renderBST :: Monad m => HtmlT m a -> m ByteString Source #

Render the HTML to a lazy ByteString, but in a monad.

This is a convenience function defined in terms of execHtmlT and toLazyByteString. Check the source if you're interested in the lower-level behaviour.

renderToFile :: FilePath -> Html a -> IO () Source #

Render the HTML to a lazy ByteString.

This is a convenience function defined in terms of execHtmlT, runIdentity and toLazyByteString. Check the source if you're interested in the lower-level behaviour.

Running

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

execHtmlT Source #

Arguments

:: Monad m 
=> HtmlT m a

The HTML to generate.

-> m Builder

The a is discarded.

Build the HTML. Analogous to execState.

You might want to use this is if you want to do something with the raw Builder. Otherwise for simple cases you can just use renderText or renderBS.

evalHtmlT Source #

Arguments

:: Monad m 
=> HtmlT m a

HTML monad to evaluate.

-> m a

Ignore the HTML output and just return the value.

Evaluate the HTML to its return value. Analogous to evalState.

Use this if you want to ignore the HTML output of an action completely and just get the result.

For using with the Html type, you'll need runIdentity e.g.

>>> runIdentity (evalHtmlT (p_ "Hello!"))
()

runHtmlT :: HtmlT m a -> m (HashMap Text Text -> Builder, a) Source #

This is the low-level way to run the HTML transformer, finally returning an element builder and a value. You can pass mempty for this argument for a top-level call. See evalHtmlT and execHtmlT for easier to use functions.

Types

type Html = HtmlT Identity Source #

Simple HTML builder type. Defined in terms of HtmlT. Check out that type for instance information.

Simple use-cases will just use this type. But if you want to transformer over Reader or something, you can go and use HtmlT.

data HtmlT m a Source #

A monad transformer that generates HTML. Use the simpler Html type if you don't want to transform over some other monad.

Instances

MFunctor HtmlT Source # 

Methods

hoist :: Monad m => (forall a. m a -> n a) -> HtmlT m b -> HtmlT n b #

MonadTrans HtmlT Source #

Used for lift.

Methods

lift :: Monad m => m a -> HtmlT m a #

MonadReader r m => MonadReader r (HtmlT m) Source # 

Methods

ask :: HtmlT m r #

local :: (r -> r) -> HtmlT m a -> HtmlT m a #

reader :: (r -> a) -> HtmlT m a #

MonadState s m => MonadState s (HtmlT m) Source # 

Methods

get :: HtmlT m s #

put :: s -> HtmlT m () #

state :: (s -> (a, s)) -> HtmlT m a #

(Monad m, (~) * a ()) => TermRaw Text (HtmlT m a) Source #

Given children immediately, just use that and expect no attributes.

Methods

termRaw :: Text -> Text -> HtmlT m a Source #

termRawWith :: Text -> [Attribute] -> Text -> HtmlT m a Source #

Monad m => Monad (HtmlT m) Source #

Basically acts like Writer.

Methods

(>>=) :: HtmlT m a -> (a -> HtmlT m b) -> HtmlT m b #

(>>) :: HtmlT m a -> HtmlT m b -> HtmlT m b #

return :: a -> HtmlT m a #

fail :: String -> HtmlT m a #

Monad m => Functor (HtmlT m) Source #

Just re-uses Monad.

Methods

fmap :: (a -> b) -> HtmlT m a -> HtmlT m b #

(<$) :: a -> HtmlT m b -> HtmlT m a #

Monad m => Applicative (HtmlT m) Source #

Based on the monad instance.

Methods

pure :: a -> HtmlT m a #

(<*>) :: HtmlT m (a -> b) -> HtmlT m a -> HtmlT m b #

(*>) :: HtmlT m a -> HtmlT m b -> HtmlT m b #

(<*) :: HtmlT m a -> HtmlT m b -> HtmlT m a #

MonadIO m => MonadIO (HtmlT m) Source #

If you want to use IO in your HTML generation.

Methods

liftIO :: IO a -> HtmlT m a #

(Monad m, ToHtml f, (~) * a ()) => TermRaw [Attribute] (f -> HtmlT m a) Source #

Given attributes, expect more child input.

Methods

termRaw :: Text -> [Attribute] -> f -> HtmlT m a Source #

termRawWith :: Text -> [Attribute] -> [Attribute] -> f -> HtmlT m a Source #

(Monad m, (~) * f (HtmlT m a)) => Term [Attribute] (f -> HtmlT m a) Source #

Given attributes, expect more child input.

Methods

term :: Text -> [Attribute] -> f -> HtmlT m a Source #

termWith :: Text -> [Attribute] -> [Attribute] -> f -> HtmlT m a Source #

(~) (* -> *) m Identity => Show (HtmlT m a) Source #

Just calls renderText.

Methods

showsPrec :: Int -> HtmlT m a -> ShowS #

show :: HtmlT m a -> String #

showList :: [HtmlT m a] -> ShowS #

(Monad m, (~) * a ()) => IsString (HtmlT m a) Source #

We pack it via string. Could possibly encode straight into a builder. That might be faster.

Methods

fromString :: String -> HtmlT m a #

((~) * a (), Monad m) => Semigroup (HtmlT m a) Source # 

Methods

(<>) :: HtmlT m a -> HtmlT m a -> HtmlT m a #

sconcat :: NonEmpty (HtmlT m a) -> HtmlT m a #

stimes :: Integral b => b -> HtmlT m a -> HtmlT m a #

((~) * a (), Monad m) => Monoid (HtmlT m a) Source #

Monoid is right-associative, a la the Builder in it.

Methods

mempty :: HtmlT m a #

mappend :: HtmlT m a -> HtmlT m a -> HtmlT m a #

mconcat :: [HtmlT m a] -> HtmlT m a #

Monad m => With (HtmlT m a -> HtmlT m a) Source #

For the contentful elements: div_

Methods

with :: (HtmlT m a -> HtmlT m a) -> [Attribute] -> HtmlT m a -> HtmlT m a Source #

Monad m => With (HtmlT m a) Source #

For the contentless elements: br_

Methods

with :: HtmlT m a -> [Attribute] -> HtmlT m a Source #

((~) * a (), (~) (* -> *) m Identity) => ToHtml (HtmlT m a) Source # 

Methods

toHtml :: Monad m => HtmlT m a -> HtmlT m () Source #

toHtmlRaw :: Monad m => HtmlT m a -> HtmlT m () Source #

Monad m => Term (HtmlT m a) (HtmlT m a) Source #

Given children immediately, just use that and expect no attributes.

Methods

term :: Text -> HtmlT m a -> HtmlT m a Source #

termWith :: Text -> [Attribute] -> HtmlT m a -> HtmlT m a Source #

data Attribute Source #

A simple attribute. Don't use the constructor, use makeAttribute.

Instances

Eq Attribute Source # 
Show Attribute Source # 
Hashable Attribute Source # 
TermRaw Text Attribute Source #

Some termRaws (like style_, title_) can be used for attributes as well as elements.

Term Text Attribute Source #

Some terms (like style_, title_) can be used for attributes as well as elements.

(Monad m, ToHtml f, (~) * a ()) => TermRaw [Attribute] (f -> HtmlT m a) Source #

Given attributes, expect more child input.

Methods

termRaw :: Text -> [Attribute] -> f -> HtmlT m a Source #

termRawWith :: Text -> [Attribute] -> [Attribute] -> f -> HtmlT m a Source #

(Monad m, (~) * f (HtmlT m a)) => Term [Attribute] (f -> HtmlT m a) Source #

Given attributes, expect more child input.

Methods

term :: Text -> [Attribute] -> f -> HtmlT m a Source #

termWith :: Text -> [Attribute] -> [Attribute] -> f -> HtmlT m a Source #

Classes

To support convenient use of HTML terms, HTML terms are overloaded. Here are the following types possible for an element term accepting attributes and/or children:

p_ :: Term arg result => arg -> result
p_ :: Monad m => [Attribute] -> HtmlT m () -> HtmlT m ()
p_ :: Monad m => HtmlT m () -> HtmlT m ()

The first is the generic form. The latter two are the possible types for an element.

Elements that accept no content are always concrete:

input_ :: Monad m => [Attribute] -> HtmlT m ()

And some attributes share the same name as attributes, so you can also overload them as attributes:

style_ :: TermRaw arg result => arg -> result
style_ :: Monad m => [Attribute] -> Text -> HtmlT m ()
style_ :: Monad m => Text -> HtmlT m ()
style_ :: Text -> Attribute

class Term arg result | result -> arg where Source #

Used to construct HTML terms.

Simplest use: p_ = term "p" yields p_.

Very overloaded for three cases:

  • The first case is the basic arg of [(Text,Text)] which will return a function that wants children.
  • The second is an arg which is HtmlT m (), in which case the term accepts no attributes and just the children are used for the element.
  • Finally, this is also used for overloaded attributes, like style_ or title_. If a return type of (Text,Text) is inferred then an attribute will be made.

The instances look intimidating but actually the constraints make it very general so that type inference works well even in the presence of things like OverloadedLists and such.

Minimal complete definition

termWith

Methods

term :: Text -> arg -> result Source #

Used for constructing elements e.g. term "p" yields p_.

termWith :: Text -> [Attribute] -> arg -> result Source #

Use this if you want to make an element which inserts some pre-prepared attributes into the element.

Instances

Term Text Attribute Source #

Some terms (like style_, title_) can be used for attributes as well as elements.

(Monad m, (~) * f (HtmlT m a)) => Term [Attribute] (f -> HtmlT m a) Source #

Given attributes, expect more child input.

Methods

term :: Text -> [Attribute] -> f -> HtmlT m a Source #

termWith :: Text -> [Attribute] -> [Attribute] -> f -> HtmlT m a Source #

Monad m => Term (HtmlT m a) (HtmlT m a) Source #

Given children immediately, just use that and expect no attributes.

Methods

term :: Text -> HtmlT m a -> HtmlT m a Source #

termWith :: Text -> [Attribute] -> HtmlT m a -> HtmlT m a Source #

class ToHtml a where Source #

Can be converted to HTML.

Minimal complete definition

toHtml, toHtmlRaw

Methods

toHtml :: Monad m => a -> HtmlT m () Source #

toHtmlRaw :: Monad m => a -> HtmlT m () Source #

Instances

ToHtml String Source # 

Methods

toHtml :: Monad m => String -> HtmlT m () Source #

toHtmlRaw :: Monad m => String -> HtmlT m () Source #

ToHtml ByteString Source #

This instance requires the ByteString to contain UTF-8 encoded text, for the toHtml method. The toHtmlRaw method doesn't care, but the overall HTML rendering methods in this module assume UTF-8.

Methods

toHtml :: Monad m => ByteString -> HtmlT m () Source #

toHtmlRaw :: Monad m => ByteString -> HtmlT m () Source #

ToHtml ByteString Source #

This instance requires the ByteString to contain UTF-8 encoded text, for the toHtml method. The toHtmlRaw method doesn't care, but the overall HTML rendering methods in this module assume UTF-8.

Methods

toHtml :: Monad m => ByteString -> HtmlT m () Source #

toHtmlRaw :: Monad m => ByteString -> HtmlT m () Source #

ToHtml Text Source # 

Methods

toHtml :: Monad m => Text -> HtmlT m () Source #

toHtmlRaw :: Monad m => Text -> HtmlT m () Source #

ToHtml Text Source # 

Methods

toHtml :: Monad m => Text -> HtmlT m () Source #

toHtmlRaw :: Monad m => Text -> HtmlT m () Source #

((~) * a (), (~) (* -> *) m Identity) => ToHtml (HtmlT m a) Source # 

Methods

toHtml :: Monad m => HtmlT m a -> HtmlT m () Source #

toHtmlRaw :: Monad m => HtmlT m a -> HtmlT m () Source #

class With a where Source #

With an element use these attributes. An overloaded way of adding attributes either to an element accepting attributes-and-children or one that just accepts attributes. See the two instances.

Minimal complete definition

with

Methods

with :: a -> [Attribute] -> a Source #

With the given element(s), use the given attributes.

Instances

Monad m => With (HtmlT m a -> HtmlT m a) Source #

For the contentful elements: div_

Methods

with :: (HtmlT m a -> HtmlT m a) -> [Attribute] -> HtmlT m a -> HtmlT m a Source #

Monad m => With (HtmlT m a) Source #

For the contentless elements: br_

Methods

with :: HtmlT m a -> [Attribute] -> HtmlT m a Source #

Re-exports