Text.Ginger.Run

Execute Ginger templates in an arbitrary monad.

Usage example:

render :: Template -> Text -> Text -> Text
render template -> username imageURL = do
   let contextLookup varName =
           case varName of
               "username" -> toGVal username
               "imageURL" -> toGVal imageURL
               _ -> def -- def for GVal is equivalent to a NULL value
       context = makeContext contextLookup
   in htmlSource $ runGinger context template

The "easy" interface

Provides a straightforward way of rendering templates monadically as well as purely.

easyRenderM :: (Monad m, ContextEncodable h, Monoid h, ToGVal (Run m h) v, ToGVal (Run m h) h) => (h -> m ()) -> v -> Template -> m (GVal (Run m h))

Simplified interface to render a ginger template "into" a monad.

easyRenderM emit context template renders the template with the given context object (which should represent some sort of dictionary-like object) by feeding any output to the emit function.

easyRender :: (ContextEncodable h, Monoid h, ToGVal (Run (Writer h) h) v, ToGVal (Run (Writer h) h) h) => v -> Template -> h

Simplified interface to render a ginger template in a pure fashion.

easyRender context template renders the template with the given context object (which should represent some sort of dictionary-like object) by returning the concatenated output.

easyContext :: (Monad m, ContextEncodable h, ToGVal (Run m h) v) => (h -> m ()) -> v -> GingerContext m h

The "direct" interface

This interface gives more control than the easy interface, at the expense of requiring more yak shaving.

runGingerT :: (ToGVal (Run m h) h, Monoid h, Monad m, Functor m) => GingerContext m h -> Template -> m (GVal (Run m h))

Monadically run a Ginger template. The m parameter is the carrier monad.

runGinger :: (ToGVal (Run (Writer h) h) h, Monoid h) => GingerContext (Writer h) h -> Template -> h

Purely expand a Ginger template. The underlying carrier monad is Writer h, which is used to collect the output and render it into a h value.

makeContext :: (VarName -> GVal (Run (Writer Html) Html)) -> GingerContext (Writer Html) Html

Deprecated: Compatibility alias for makeContextHtml

makeContextM :: (Monad m, Functor m) => (VarName -> Run m Html (GVal (Run m Html))) -> (Html -> m ()) -> GingerContext m Html

Deprecated: Compatibility alias for makeContextHtmlM

makeContext' :: Monoid h => (VarName -> GVal (Run (Writer h) h)) -> (GVal (Run (Writer h) h) -> h) -> Maybe (Newlines h) -> GingerContext (Writer h) h

Create an execution context for runGinger. The argument is a lookup function that maps top-level context keys to ginger values. makeContext is a specialized version of makeContextM, targeting the Writer Html monad (which is what is used for the non-monadic template interpreter runGinger).

The type of the lookup function may look intimidating, but in most cases, marshalling values from Haskell to Ginger is a matter of calling toGVal on them, so the 'GVal (Run (Writer Html))' part can usually be ignored. See the GVal module for details.

makeContextM' :: (Monad m, Functor m) => (VarName -> Run m h (GVal (Run m h))) -> (h -> m ()) -> (GVal (Run m h) -> h) -> Maybe (Newlines h) -> GingerContext m h

Create an execution context for runGingerT. Takes a lookup function, which returns ginger values into the carrier monad based on a lookup key, and a writer function (outputting HTML by whatever means the carrier monad provides, e.g. putStr for IO, or tell for Writers).

makeContextHtml :: (VarName -> GVal (Run (Writer Html) Html)) -> GingerContext (Writer Html) Html

makeContextHtmlM :: (Monad m, Functor m) => (VarName -> Run m Html (GVal (Run m Html))) -> (Html -> m ()) -> GingerContext m Html

makeContextText :: (VarName -> GVal (Run (Writer Text) Text)) -> GingerContext (Writer Text) Text

makeContextTextM :: (Monad m, Functor m) => (VarName -> Run m Text (GVal (Run m Text))) -> (Text -> m ()) -> GingerContext m Text

The context type

data GingerContext m h

Execution context. Determines how to look up variables from the environment, and how to write out template output.

The Run monad

type Run m h = StateT (RunState m h) (ReaderT (GingerContext m h) m)

Internal type alias for our template-runner monad stack.

liftRun :: Monad m => m a -> Run m h a

Lift a value from the host monad m into the Run monad.

liftRun2 :: Monad m => (a -> m b) -> a -> Run m h b

Lift a function from the host monad m into the Run monad.

Helper functions for interpreting argument lists

extractArgs :: [Text] -> [(Maybe Text, a)] -> (HashMap Text a, [a], HashMap Text a, [Text])

Match args according to a given arg spec, Python style. The return value is a triple of (matched, args, kwargs, unmatchedNames), where matches is a hash map of named captured arguments, args is a list of remaining unmatched positional arguments, kwargs is a list of remaining unmatched named arguments, and unmatchedNames contains the argument names that haven't been matched.

extractArgsT :: ([Maybe a] -> b) -> [Text] -> [(Maybe Text, a)] -> Either ([a], HashMap Text a, [Text]) b

Parse argument list into type-safe argument structure.

extractArgsL :: [Text] -> [(Maybe Text, a)] -> Either ([a], HashMap Text a, [Text]) [Maybe a]

Parse argument list into flat list of matched arguments.

extractArgsDefL :: [(Text, a)] -> [(Maybe Text, a)] -> Either ([a], HashMap Text a, [Text]) [a]