Text.Haiji

Haiji is a template engine which is subset of Jinja2. This is designed to free from the unintended rendering result by strictly typed variable interpolation.

Rendering result will be same as Jinja2's one. However, Haiji doesn't aim to be Jinja2. Some feature and built-in Test/Function/Filter of Jinja2 allow rendering time type inspection. Haiji will not support these type unsafe features. Haiji generates a statically typed template by Template Haskell, and check that a given dictionary includes enough information to render template.

{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE QuasiQuotes #-}
{-# LANGUAGE DataKinds #-}
module Main where

import Data.Default
import Text.Haiji
import qualified Data.Text as T
import qualified Data.Text.Lazy as LT
import qualified Data.Text.Lazy.IO as LT

main :: IO ()
main = LT.putStr
       $ render $(haijiFile def "example.tmpl")
       $ [key|a_variable|] ("Hello,World!" :: LT.Text) `merge`
         [key|navigation|] [ [key|caption|] cap `merge` [key|href|] href
                           | (cap, href) <- [ ("A", "content/a.html")
                                            , ("B", "content/b.html")
                                            ] :: [ (T.Text, String) ]
                           ] `merge`
         [key|foo|] (1 :: Int) `merge`
         [key|bar|] ("" :: String)

Typed Template

{{ foo }}

For example, this Jinja2 template requires "foo". A dictionary which provides a variable "foo" is required to render it. If a variable "foo" does not exist in a given dictionary, Jinja2 evaluates it to an empty string by default, whereas haiji treats this case as compile error.

data Template dict

Haiji template

Generators

haiji :: Environment -> QuasiQuoter

QuasiQuoter to generate a Haiji template

haijiFile :: Quasi q => Environment -> FilePath -> q Exp

Generate a Haiji template from external file

Renderer

render :: Template dict -> dict -> Text

Render Haiji template with given dictionary

Rendering Environment

data Environment

A template environment

Instances

Eq Environment

Defined in Text.Haiji.Types

Methods

(==) :: Environment -> Environment -> Bool

(/=) :: Environment -> Environment -> Bool

Show Environment

Defined in Text.Haiji.Types

Methods

showsPrec :: Int -> Environment -> ShowS

show :: Environment -> String

showList :: [Environment] -> ShowS

Default Environment

Defined in Text.Haiji.Types

Methods

def :: Environment

autoEscape :: Environment -> Bool

XML/HTML autoescaping

Dictionary

data Dict (kv :: [*])

Type level Dictionary

Instances

ToJSON (Dict s) => Show (Dict s)

Defined in Text.Haiji.Dictionary

Methods

showsPrec :: Int -> Dict s -> ShowS

show :: Dict s -> String

showList :: [Dict s] -> ShowS

ToJSON (Dict ([] :: [Type]))

Defined in Text.Haiji.Dictionary

Methods

toJSON :: Dict [] -> Value

toEncoding :: Dict [] -> Encoding

toJSONList :: [Dict []] -> Value

toEncodingList :: [Dict []] -> Encoding

toDict :: (KnownSymbol k, Typeable x) => x -> Dict '[k :-> x]

Create single element dictionary (with TypeApplications extention)

empty :: Dict '[]

Empty dictionary

Builder

key :: QuasiQuoter

Generate a dictionary with single item

merge :: Dict xs -> Dict ys -> Dict (Merge xs ys)