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Today's Topics:
1. Re: Typing/N00b question/My first haskell (Bryan Hunt)
2. data design for a questionnaire (retitled + update) (Alia)
3. Re: data design for a questionnaire (retitled + update) (Alia)
4. User defined operators : setting precedence (Hugo Ferreira)
5. Re: User defined operators : setting precedence (Antoine Latter)
6. Re: Need advice on R vs Haskell (Allen S. Rout)
7. Re: User defined operators : setting precedence (Hugo Ferreira)
----------------------------------------------------------------------
Message: 1
Date: Mon, 21 Nov 2011 12:04:04 +0000
From: Bryan Hunt <[email protected]>
Subject: Re: [Haskell-beginners] Typing/N00b question/My first haskell
To: Haskell Beginners List <[email protected]>
Message-ID: <[email protected]>
Content-Type: text/plain; charset=us-ascii
Thank you for your helpful replies, program works correctly now:
module Main where
ageJudge age
| age >= 40 = "You're too old!"
| age <= 30 = "You're too young"
| otherwise = "Not in the programming age range.."
main = do
putStrLn "What is your name?"
name <- getLine
putStrLn ("Nice to meet you, " ++ name ++ "!")
putStrLn "What is your age?"
age <- getLine
let inpIntegral = (read age)::Int
putStrLn ( "We decided:\n" ++ ageJudge inpIntegral )
------------------------------
Message: 2
Date: Mon, 21 Nov 2011 05:46:28 -0800 (PST)
From: Alia <[email protected]>
Subject: [Haskell-beginners] data design for a questionnaire (retitled
+ update)
To: "[email protected]" <[email protected]>
Message-ID:
<[email protected]>
Content-Type: text/plain; charset=iso-8859-1
I've retitled this post just in case (-:
Having spent some more time on the prior post (questionnaire data design
patterns), I've managed
to produce a version that allows for heterogeneous lists but that seems to
necessarily involve existential
quantification.
Three question remain:
(1) figure out how to show 'questions' in version3.hs (I'm stumped so far)
(2) figure out how to make Question and its subtypes polymorphic in the context
of existential quantification:
??? such that you can have a Choice a where a is an Int and another Choice
Double, etc... yet still allow for
??? heterogeneous lists so that questions = [open ...., test ...., choice ...]
would still be possible.
(3) translate version3.hs to use records (if possible)
<version3.hs>
{-# LANGUAGE ExistentialQuantification #-}
{-# LANGUAGE TypeSynonymInstances #-}
module Main where
import Text.Show.Functions
-- dummy funcs for now
class Question_ a where
??? ask??????? :: a -> String
??? view?????? :: a -> String
??? parse????? :: a -> String
???
data Question = forall a. Question_ a => Question a
type Name????????? = String
type QString?????? = String
type AnswerType??? = String
type CorrectAnswer = String
type Option??????? = (String, String)
type Options?????? = [Option]
-- question types
data Open????? = Open?? Name QString AnswerType
data Test????? = Test?? Name QString AnswerType CorrectAnswer
data Choice??? = Choice Name QString AnswerType CorrectAnswer Options
instance Question_ Open where
??? ask?? (Open n q a) = n
??? view? (Open n q a) = q
??? parse (Open n q a) = a
instance Question_ Test where
??? ask?? (Test n q a c) = n ++ c
??? view? (Test n q a c) = q ++ c
??? parse (Test n q a c) = a ++ c
instance Question_ Choice where
??? ask?? (Choice n q a c os) = n ++ c
??? view? (Choice n q a c os) = q ++ c
??? parse (Choice n q a c os) = a ++ c
instance Question_ Question where
??? ask?? (Question q) = ask?? q
??? view? (Question q) = view? q
??? parse (Question q) = parse q
--
-- Smart constructor
--
open :: Name -> QString -> AnswerType -> Question
open n q a = Question (Open n q a)
test :: Name -> QString -> AnswerType -> CorrectAnswer -> Question
test n q a c = Question (Test n q a c)
choice :: Name -> QString -> AnswerType -> CorrectAnswer -> Options -> Question
choice n q a c os = Question (Choice n q a c os)
questions :: [Question]
questions = [ open?? "q1" "what is your name" "str"
??????????? , test?? "q2" "what is 1+1?"????? "int" "2"
??????????? , choice "q3" "what is 2+2?"????? "int" "4" [("a", "4")]
??????????? ]
</version.hs>
Alia
??????????? ]
------------------------------
Message: 3
Date: Mon, 21 Nov 2011 06:04:36 -0800 (PST)
From: Alia <[email protected]>
Subject: Re: [Haskell-beginners] data design for a questionnaire
(retitled + update)
To: "[email protected]" <[email protected]>
Message-ID:
<[email protected]>
Content-Type: text/plain; charset="iso-8859-1"
As a followup, I just received a simpler and more elegant solution due to
Lorenzo Bolla which involves wrapping
the question type in another type and achieves the objective nicely. I think
this is much cleaner than
using existential types as per my prior posting.
<version4.hs>
module Main where
import Text.Show.Functions
-- type converters
str = id
int s = read s :: Int
float s = read s :: Double
data QuestionType = Open | Test | Choice deriving (Show, Eq)
data Question a = Question
??? { questionName??? :: String
??? , questionText??? :: String
??? , questionType??? :: QuestionType
??? , answerFunc????? :: (String -> a)
??? , correctAnswer?? :: Maybe a
??? , options???????? :: Maybe [(String, a)]
??? } deriving (Show)
data Question' = QuestionS (Question String) | QuestionI (Question Int)
deriving (Show)
data QuestionSet a = QuestionSet
??? { qsetTitle???? :: String
??? , qsetQuestions :: [Question']
??? } deriving (Show)
data Questionnaire a = Questionnaire
??? { questionnaireTitle??????? :: String
??? , questionnaireQuestionSets :: [QuestionSet a]
??? } deriving (Show)
q1 = Question
??? { questionName? = "q1"
??? , questionText? = "What is our name?"
??? , questionType? = Open
??? , answerFunc??? = id
??? , correctAnswer = Nothing
??? , options?????? = Nothing
??? }
q2 = Question
??? { questionName? = "q2"
??? , questionText? = "What is 1+1?"
??? , questionType? = Test
??? , answerFunc??? = int
??? , correctAnswer = Just 2
??? , options?????? = Nothing
??? }
q3 = Question
??? { questionName? = "q2"
??? , questionText? = "What is 2+1?"
??? , questionType? = Choice
??? , answerFunc??? = int
??? , correctAnswer = Just 3
??? , options?????? = Just [("a", 2), ("b", 3), ("c", 4)]
??? }
qset = QuestionSet
??? { qsetTitle???? = "simple questions"
??? , qsetQuestions = [QuestionS q1, QuestionI q2, QuestionI q3]
??? }
questionnaire = Questionnaire
??? { questionnaireTitle??????? = "a questionnaire"
??? , questionnaireQuestionSets = [qset]
??? }
</version4.hs>
Alia
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Message: 4
Date: Mon, 21 Nov 2011 15:34:23 +0000
From: Hugo Ferreira <[email protected]>
Subject: [Haskell-beginners] User defined operators : setting
precedence
To: "[email protected]" <[email protected]>
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-15; format=flowed
Hello,
Can anyone point me to some documentation that describes
how one may set precedence in a user defined operators?
I have composition operators so that I can write:
let ruleSuffixCapsFreq = ruleT |> suffixT .> capitalizeT .> freqT
but I seem to be forced to write:
let ruleSuffixCapsFreq = ruleT |> (suffixT .> capitalizeT .> freqT)
and I would like to avoid this.
TIA,
Hugo F.
------------------------------
Message: 5
Date: Mon, 21 Nov 2011 09:47:45 -0600
From: Antoine Latter <[email protected]>
Subject: Re: [Haskell-beginners] User defined operators : setting
precedence
To: Hugo Ferreira <[email protected]>
Cc: "[email protected]" <[email protected]>
Message-ID:
<CAKjSnQFRM7j_iy7=wwpc1bwtfyxfrcbue7ro59wyqrzp-xt...@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
On Mon, Nov 21, 2011 at 9:34 AM, Hugo Ferreira <[email protected]> wrote:
> Hello,
>
> Can anyone point me to some documentation that describes
> how one may set precedence in a user defined operators?
> I have composition operators so that I can write:
>
> ?let ruleSuffixCapsFreq = ruleT |> suffixT .> capitalizeT .> freqT
>
> but I seem to be forced to write:
>
> ?let ruleSuffixCapsFreq = ruleT |> (suffixT .> capitalizeT .> freqT)
>
> and I would like to avoid this.
>
Hello,
Here's a brief introduction to Haskell fixity declarations:
http://www.haskell.org/tutorial/functions.html#sect3.2.2
Here's the relevant part of the language definition, which includes a
precedence table for the operators that ship with the language:
http://www.haskell.org/onlinereport/haskell2010/haskellch4.html#x10-820004.4.2
Antoine
> TIA,
> Hugo F.
>
>
> _______________________________________________
> Beginners mailing list
> [email protected]
> http://www.haskell.org/mailman/listinfo/beginners
>
------------------------------
Message: 6
Date: Mon, 21 Nov 2011 11:15:01 -0500
From: "Allen S. Rout" <[email protected]>
Subject: Re: [Haskell-beginners] Need advice on R vs Haskell
To: [email protected]
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 11/20/2011 12:57 AM, haskell heath wrote:
> [ I've dabbled in lots of stuff, which language should I use for what?]
and
> I'm new to Haskell and I can't really call myself a decent
> programmer in any other language. Do you think it's wrong to think
> that I can contribute to the statistics library?
I'm a journeyman R coder and a bare novice at Haskell. What springs to
my mind here is, what's your primary goal: to enhance the statistical
toolset available in Haskell, or to accomplish a task?
If the former, then I think the critical question isn't your language
competence but your statistical props; if you watch the R devel list
for any duration, you'll see how deeply the real stats folks treat these
problems; to have a broken tool (and not know it) is often worse than
to have no tool. If you've got the stats clue, then by all means
soldier on. Subject Matter Experts rock. :)
If your goal is to accomplish your task, then I suggest that R is
absolutely the superior environment for statistical thinking these days.
Cobble together whatever data-collection bits you need in whatever
toolset is convenient, and if you're scraping web, then node.js is as
good a place to start as any. Drop CSV files from your scraping, and
go to town in R.
- Allen S. Rout
------------------------------
Message: 7
Date: Mon, 21 Nov 2011 16:21:53 +0000
From: Hugo Ferreira <[email protected]>
Subject: Re: [Haskell-beginners] User defined operators : setting
precedence
To: Antoine Latter <[email protected]>
Cc: "[email protected]" <[email protected]>
Message-ID: <[email protected]>
Content-Type: text/plain; charset=UTF-8; format=flowed
Antoine,
On 11/21/2011 03:47 PM, Antoine Latter wrote:
> On Mon, Nov 21, 2011 at 9:34 AM, Hugo Ferreira<[email protected]> wrote:
>> Hello,
>>
>> Can anyone point me to some documentation that describes
>> how one may set precedence in a user defined operators?
>> I have composition operators so that I can write:
>>
>> let ruleSuffixCapsFreq = ruleT |> suffixT .> capitalizeT .> freqT
>>
>> but I seem to be forced to write:
>>
>> let ruleSuffixCapsFreq = ruleT |> (suffixT .> capitalizeT .> freqT)
>>
>> and I would like to avoid this.
>>
>
> Hello,
>
> Here's a brief introduction to Haskell fixity declarations:
>
> http://www.haskell.org/tutorial/functions.html#sect3.2.2
>
> Here's the relevant part of the language definition, which includes a
> precedence table for the operators that ship with the language:
>
> http://www.haskell.org/onlinereport/haskell2010/haskellch4.html#x10-820004.4.2
>
Exactly what I was looking for.
Thank you,
Hugo F.
> Antoine
>
>> TIA,
>> Hugo F.
>>
>>
>> _______________________________________________
>> Beginners mailing list
>> [email protected]
>> http://www.haskell.org/mailman/listinfo/beginners
>>
>
------------------------------
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