Data.Text.Format.Heavy.Parse.Shell

This module defines shell-like syntax of format strings, generally described as "any part after dollar sign is a variable substitution".

Examples of valid variable substitutions are:

• "Simple: ${}". Note that to have auto-numbered placeholders in this syntax, you have to write ${}; both dollar sign and braces are necessary.
• "Numbered: $1" or "Numbered: ${1}".
• "Named: $var" or "Named: ${var}".
• "Specifying variable formatting: ${var:+8.4}". To specify variable format, you have to use braces.

This syntax is not the default, so to use it you have to explicitly call parseShellFormat':

{-# LANGUAGE OverloadedStrings #-}
module Main where

import Data.Time
import qualified Data.Text.Lazy.IO as TLIO
import Data.Text.Format.Heavy
import Data.Text.Format.Heavy.Parse.Shell

main :: IO ()
main = do
  name <- getLine
  time <- getZonedTime
  TLIO.putStrLn $ format (parseShellFormat' "Hello, ${}! It is ${:%H:%M:%S} now.") (name, time)

Parse functions

parseShellFormat :: Text -> Either ParseError Format

Parse string format definition.

parseShellFormat' :: Text -> Format

Version of parseShellFormat which throws error in case of syntax error in the formatting string.

Parsec functions

pShellFormat :: Parser Format

Parsec parser for string format.