{-# LANGUAGE OverloadedStrings, OverloadedLists, RecursiveDo #-} module Pinchot.Examples.Postal where import Pinchot import Data.Monoid ((<>)) -- | A grammar for simple U.S. postal addresses. This example would never -- hold up to real-world usage but it gives you a flavor of how -- Pinchot works. -- -- The grammar is ambiguous. postal :: Pinchot Char (Rule Char) postal = mdo digit <- terminal "Digit" (include '0' '9') "digit from 0 to 9" digits <- list1 "Digits" digit letter <- terminal "Letter" (include 'a' 'z' <> include 'A' 'Z') "letter from A to Z" north <- terminal "North" (solo 'N') south <- terminal "South" (solo 'S') east <- terminal "East" (solo 'E') west <- terminal "West" (solo 'W') direction <- nonTerminal "Direction" [ ("DNorth", [north]), ("DSouth", [south]), ("DEast", [east]) , ("DWest", [west])] street <- terminalSeq "Street" ['S', 't'] avenue <- terminalSeq "Avenue" ['A', 'v', 'e'] way <- terminalSeq "Way" ['W', 'a', 'y'] boulevard <- terminalSeq "Boulevard" ['B', 'l', 'v', 'd'] suffix <- nonTerminal "Suffix" [ ("SStreet", [street]), ("SAvenue", [avenue]), ("SWay", [way]) , ("SBoulevard", [boulevard])] space <- terminal "Space" (solo ' ') comma <- terminal "Comma" (solo ',') -- You could do this with 'many' but this demonstrates how to write -- a recurvsive rule. letters <- nonTerminal "Letters" [ ("NoLetter", []) , ("ConsLetter", [letter, letters]) ] -- Named "PostalWord" to avoid clash with Prelude.Word word <- record "PostalWord" [letter, letters] preSpacedWord <- nonTerminal "PreSpacedWord" [("PreSpacedWord", [space, word])] preSpacedWords <- list "PreSpacedWords" preSpacedWord words <- nonTerminal "Words" [("Words", [word, preSpacedWords])] number <- wrap "Number" digits streetName <- wrap "StreetName" words city <- wrap "City" words state <- wrap "State" word zipCode <- wrap "ZipCode" digits directionSpace <- nonTerminal "DirectionSpace" [("DirectionSpace", [direction, space])] spaceSuffix <- nonTerminal "SpaceSuffix" [("SpaceSuffix", [space, suffix])] optDirection <- option "MaybeDirection" directionSpace optSuffix <- option "MaybeSuffix" spaceSuffix address <- record "Address" [ number, space, optDirection, streetName, optSuffix, comma, space, city, comma, space, state, space, zipCode ] return address