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Today's Topics:

   1.  I have question about Haskell (Eunsu Kim)


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Message: 1
Date: Thu, 21 Apr 2016 22:33:33 -0500
From: Eunsu Kim <wntuw...@gmail.com>
To: beginners@haskell.org
Subject: [Haskell-beginners] I have question about Haskell
Message-ID: <796b2363-7d2a-4b26-9fb7-0c785e174...@gmail.com>
Content-Type: text/plain; charset="utf-8"

Hi

i have a problem in my code!

here is my code:

-- Baic I/O and Loop (50 Points)

evalpoly = do   putStr "What is the degree of polynomial: "
                degree <- getLine
                coeffs <- (funcOfCoeff ((read degree::Int)+1) [])
                putStr "What value do you want to evaluate at: "
                value <- getLine        
                putStr "The value of the polynomial is: "
                putStr (show (polyEvaluate (coeffs) (read value :: Float) ))
                putStr "\n"

--function loop to get coefficient--

funcOfCoeff 0 coeffs = do               --to check the degree of 0
                        return coeffs   --return list of coefficient

funcOfCoeff degree coeffs = do  
                        putStr ("What is the x^" ++ show(degree-1))     
                        putStr " coefficient: "
                        coeff <- getLine
                        loop <- funcOfCoeff (degree-1) ((read coeff :: Int) : 
coeffs)
                        return loop


                        
polyEvaluate (coeffs) x = do
                        powers <- zip coeffs (iterate (+1) 0)
                        result <- map (\(a,b)-> a+b) powers     ?PROBLEM IS 
HERE!!!!
                        return result

here is error message:



in very bottom function (polyEvaluate), why is not working ?result <- map 
(\(a,b) -> a+b) powers? ???

in Prelude, it is working



Thanks!
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