doctemplates
This is the templating system used by pandoc. It was formerly
be a module in pandoc. It has been split off to make it easier
to use independently.
Example:
{-# LANGUAGE OverloadedStrings #-}
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.