----------------------------------------------------------------
-- Purpose:	Scaffolding for 433-141 Spell Checker Project --
-- Authors:	Martin Sulzmann, sulzmann@cs.mu.oz.au         --
--		Alistair Moffat, alistair@cs.mu.oz.au         --
-- Students:	DO NOT EDIT OR CHANGE THIS FILE               --
----------------------------------------------------------------

module SPCLib where


----------------------
-- Type definitions --
----------------------


-- MyWord is a list of characters

type MyWord = String

-- Dictionary is a list of words

type Dictionary = [MyWord]

-- CorrectionList is a list of tuples, where each tuple includes
-- a line number, a word thought to be in error, and a list of
-- possible corrected spellings

type LineNum = Int
type CorrectionList = [(LineNum, MyWord, [MyWord])]

-- A WordList is the same thing, but without the list of possible
-- correct spellings

type WordList = [(LineNum, MyWord)]

-- SpellCheck describes a function which takes a dictionary and a string,
-- and checks the words in the string against the dictionary and outputs
-- a list of possibly misspelt words and possible replacement spellings

type SpellCheck = Dictionary -> String -> IO ()

--------------------------
-- Function definitions --
--------------------------

-- noAnswers is what you say when you can't make any suggestions about
-- how an incorrect word should be spelt

noAnswers :: [MyWord]
noAnswers = ["sorry, no suggestions can be made"]

-- prepareWords processes a string into a WordList, by breaking
-- into lines and then words, and tagging each word with its line number

prepareWords :: (String -> [MyWord]) -> String -> WordList
prepareWords getWords string
	= [(num, w) | (num, line) <- zip [1..] (lines string),
		w <- getWords line]

-- presentNicely takes a CorrectionList and generates a formatted
-- output string, ready for putStr

presentNicely :: CorrectionList -> String
presentNicely [] = ""
presentNicely ((num, w, cs) : numwcs)
	= "on line " ++ show num ++ " word " ++ show w
	  ++ " might in fact be one of:" 
	  ++ concat (map ((++) "\n\t") cs)
	  ++ "\n"
	  ++ presentNicely numwcs

-- A dictionary for you to use in your testing

smalldict :: Dictionary
smalldict = [
	"a", "all", "and", "as", "bell", "cockle", "contrary",
	"does", "fleece", "fly", "garden", "glass", "grow", "had",
	"he", "how", "in", "it", "lamb", "little", "maid",
	"marigold", "mary", "marry", "pretty", "quite", "row",
	"said", "she", "shelf", "shell", "silver", "some", "snow",
	"spy", "the", "they", "upon", "was", "what", "when", "while",
	"white", "who", "why", "will", "with", "your" 
	]

-- And some sample strings...

	
mary1 = "Mary had a little lamb little lamb little lamb\n" ++
	"Mary had a little lamb\nit's fleece was white as snow\n"

mary2 = "Mary Mry\nquite contrary,\nhow does your garden grow?\n" ++
	"With silver bells and cocle shells,\nand pretty maids alll in a row.\n"

mary3 = "Mary spies some little flies, little flies, little flies;\n" ++
	"Mary spies sme little flys\nupon the wine glass shelves."