| Copyright | Copyright (C) 2009-2016 John MacFarlane |
|---|---|
| License | BSD3 |
| Maintainer | John MacFarlane <jgm@berkeley.edu> |
| Stability | alpha |
| Portability | portable |
| Safe Haskell | None |
| Language | Haskell2010 |
Text.DocTemplates
Description
A simple templating system with variable substitution and conditionals. This module was formerly part of pandoc and is used for pandoc's templates. The following program illustrates its use:
import Data.Text
import Data.Aeson
import Text.DocTemplates
data Employee = Employee { firstName :: String
, lastName :: String
, salary :: Maybe Int }
instance ToJSON Employee where
toJSON e = object [ "name" .= object [ "first" .= firstName e
, "last" .= lastName e ]
, "salary" .= salary e ]
template :: Text
template = "$for(employee)$Hi, $employee.name.first$. $if(employee.salary)$You make $employee.salary$.$else$No salary data.$endif$$sep$\n$endfor$"
main = case compileTemplate template of
Left e -> error e
Right t -> putStrLn $ renderTemplate t $ object
["employee" .=
[ Employee "John" "Doe" Nothing
, Employee "Omar" "Smith" (Just 30000)
, Employee "Sara" "Chen" (Just 60000) ]
]A slot for an interpolated variable is a variable name surrounded
by dollar signs. To include a literal $ in your template, use
$$. Variable names must begin with a letter and can contain letters,
numbers, _, -, and ..
The values of variables are determined by a JSON object that is
passed as a parameter to renderTemplate. So, for example,
title will return the value of the title field, and
employee.salary will return the value of the salary field
of the object that is the value of the employee field.
The value of a variable will be indented to the same level as the variable.
A conditional begins with $if(variable_name)$ and ends with $endif$.
It may optionally contain an $else$ section. The if section is
used if variable_name has a non-null value, otherwise the else section
is used.
Conditional keywords should not be indented, or unexpected spacing problems may occur.
The $for$ keyword can be used to iterate over an array. If
the value of the associated variable is not an array, a single
iteration will be performed on its value.
You may optionally specify separators using $sep$, as in the
example above.
- renderTemplate :: (ToJSON a, TemplateTarget b) => Template -> a -> b
- applyTemplate :: (ToJSON a, TemplateTarget b) => Text -> a -> Either String b
- class TemplateTarget a where
- varListToJSON :: [(String, String)] -> Value
- compileTemplate :: Text -> Either String Template
- data Template
Documentation
renderTemplate :: (ToJSON a, TemplateTarget b) => Template -> a -> b Source #
Render a compiled template using context to resolve variables.
applyTemplate :: (ToJSON a, TemplateTarget b) => Text -> a -> Either String b Source #
Combines renderTemplate and compileTemplate.
class TemplateTarget a where Source #
Minimal complete definition