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Today's Topics:
1. Re: data design for a questionnaire (retitled + update) (Alia)
2. Re: data design for a questionnaire (retitled + update) (Alia)
3. Re: Problems linking code from the book Haskell School of
Expression (Philippe Sismondi)
----------------------------------------------------------------------
Message: 1
Date: Sat, 26 Nov 2011 06:10:03 -0800 (PST)
From: Alia <[email protected]>
Subject: Re: [Haskell-beginners] data design for a questionnaire
(retitled + update)
To: "[email protected]" <[email protected]>
Cc: "[email protected]" <[email protected]>
Message-ID: <[email protected]>
Content-Type: text/plain; charset="iso-8859-1"
?David McBride wrote:
> Why not have:
> data Question = Question
>???? { questionName??? :: Name
>???? , questionText??? :: QuestionText
>???? , questionType??? :: QuestionType
>???? , answerFunc????? :: (String -> AnswerType)
>???? , correctAnswer? :: Maybe AnswerType
>???? , options??????? :: Maybe [Option AnswerType]
>???? } deriving (Show)
> data AnswerType = AnsD Double | AnsS String | AnsI Integer
>?????????????????? deriving (Show, Read)
> Then, I'd personally make another change, why would you have a flat
> structure with a questionType and then optional correctAnswer and
> options fields?? There's no type safety in that.? I'd try:
> data Answer = StraightAnswer (String -> AnswerType) | MultipleChoice
> AnswerType [Option AnswerType]
> data Question = Question
>???? { questionName??? :: Name
>???? , questionText??? :: QuestionText
>???? , answerFunc????? :: (String -> AnswerType)
>???? , answer????????????? :: Answer
>???? } deriving (Show)
> If you are storing answers as string, just store them as "AnsD 5.589",
> "AnsS \"Constantiople\"".? Then with the read instance you can go:
> let answer = read x :: AnswerType
Thank you very much for the reply which is eye-opening. But I do have to spend
time
implementing your revised schema in the prior question handling functions to
get my head around it? (-:
Best,
Alia
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Message: 2
Date: Sat, 26 Nov 2011 09:20:55 -0800 (PST)
From: Alia <[email protected]>
Subject: Re: [Haskell-beginners] data design for a questionnaire
(retitled + update)
To: "[email protected]" <[email protected]>
Cc: "[email protected]" <[email protected]>
Message-ID:
<[email protected]>
Content-Type: text/plain; charset="iso-8859-1"
Hi folks,
Just to wrap things up: I think I'm satisfied with the design below, mostly due
to David McBride's advice.
My final code is a slight variation on his suggested course, but not by much.
Many thanks to all those
who replied and helped with this problem.
<survey.final.hs>
module Main where
import Text.Show.Functions
type Name??????????? = String
type QuestionText??? = String
type Score?????????? = Double
type Option a??????? = (String, a)
-- type converters
convert x = read x :: AnswerType
str s = convert ("AnsS \""++ s ++"\"")
int s = convert ("AnsI "++s)
double s = convert ("AnsD "++s)
data AnswerType = AnsD Double
??????????????? | AnsS String
??????????????? | AnsI Integer
????????????????? deriving (Show, Read, Eq)
data Answer = AnyAnswer
??????????? | TestAnswer AnswerType
??????????? | MultipleChoice AnswerType [Option AnswerType]
????????????? deriving (Show)
data Question = Question
??? { questionName??? :: Name
??? , questionText??? :: QuestionText
??? , answerFunc????? :: String -> AnswerType
??? , answer????????? :: Answer
??? } deriving (Show)
data QuestionSet = QuestionSet
??? { qsetTitle???? :: Name
??? , qsetQuestions :: [Question]
??? , qsetPoints??? :: Score
??? } deriving (Show)
data Survey = Survey
??? { surveyTitle??????? :: Name
??? , surveyQuestionSets :: [QuestionSet]
??? } deriving (Show)
askQuestion?? :: Question -> IO String
askQuestion q = do
??? putStrLn $ questionText q
??? getLine
askQuestionSet :: QuestionSet -> IO [String]
askQuestionSet qs = mapM askQuestion (qsetQuestions qs)
takeQuestionSet :: QuestionSet -> IO [Bool]
takeQuestionSet qs = do
??? answers <- askQuestionSet qs
??? return (testQuestionSet qs answers)
testQuestion :: Question -> String -> Bool
testQuestion q ans = case answer q of
??? AnyAnswer?????????? -> not (null ans)
??? TestAnswer c??????? -> c == answerFunc q ans
??? MultipleChoice c os -> c == answerFunc q ans
testQuestionSet :: QuestionSet -> [String] -> [Bool]
testQuestionSet qs = zipWith testQuestion (qsetQuestions qs)
evalQuestionSet :: QuestionSet -> [String] -> Score
evalQuestionSet qs as = (total_correct / total_questions) * score
??? where
??????? total_questions = fromIntegral (length $ qsetQuestions qset)
??????? total_correct = fromIntegral (length $ filter (== True)
(testQuestionSet qset as))
??????? score = qsetPoints qset
-- TESTING
q1 = Question
??? { questionName? = "q1"
??? , questionText? = "What is our name?"
??? , answerFunc??? = str
??? , answer??????? = AnyAnswer
??? }
q2 = Question
??? { questionName? = "q2"
??? , questionText? = "What is 1+1?"
??? , answerFunc??? = int
??? , answer??????? = TestAnswer (AnsI 2)
??? }
q3 = Question
??? { questionName? = "q3"
??? , questionText? = "What is 2+1?"
??? , answerFunc??? = int
??? , answer??????? = MultipleChoice (AnsI 3) [ ("a", AnsI 2)
????????????????????????????????????????????? , ("b", AnsI 3)
????????????????????????????????????????????? , ("c", AnsI 4)
????????????????????????????????????????????? ]
??? }
q4 = Question
??? { questionName? = "q4"
??? , questionText? = "What is 2.0 + 1.5 ?"
??? , answerFunc??? = double
??? , answer??????? = MultipleChoice (AnsD 3.5) [ ("a", AnsD 2.1)
??????????????????????????????????????????????? , ("b", AnsD 3.5)
??????????????????????????????????????????????? , ("c", AnsD 4.4)
??????????????????????????????????????????????? ]
??? }
qset = QuestionSet
??? { qsetTitle???? = "simple questions"
??? , qsetQuestions = [ q1, q2, q3, q4 ]
??? , qsetPoints??? = 100.0
??? }
survey = Survey
??? { surveyTitle??????? = "a survey"
??? , surveyQuestionSets = [qset]
??? }
t1 = evalQuestionSet qset ["1", "2", "3", "4"]
</survey.final.hs>
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Message: 3
Date: Sat, 26 Nov 2011 16:11:02 -0500
From: Philippe Sismondi <[email protected]>
Subject: Re: [Haskell-beginners] Problems linking code from the book
Haskell School of Expression
To: Beginners Haskell <[email protected]>
Message-ID: <[email protected]>
Content-Type: text/plain; charset="us-ascii"
On 2011-11-25, at 10:53 PM, Brandon Allbery wrote:
> On Fri, Nov 25, 2011 at 22:30, Philippe Sismondi <[email protected]> wrote:
> Well, I just realized that since I only need this for learning purposes (not
> production code) I may as well do it under linux. I have my linux box on a
> kvm with the mac. (That's my current form of "virtualization" ;-) I'll do
> this if ubuntu and HP work well together. Thoughts?
>
> That's where I've ended up for my xmonad development (well, still setting it
> up), since xmonad is crashing when I use a ghc that is built against MacPorts
> (both MP's own GHC and a locally built up to date haskell-platform) which I
> need for X11-xft :/
>
I am now set up on ubuntu 11.04. Code using Graphics.SOE.Gtk is running without
a hitch.
Thanks again.
> --
> brandon s allbery [email protected]
> wandering unix systems administrator (available) (412) 475-9364 vm/sms
>
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