Hi all, I am trying to retrieve the decimal portion of a Double. My code is: getDecimal x = x - floor(x) I would expect the following: Main> getDecimal 1.23 0.23 :: [Double] but instead, I get: Main> getDecimal 1.23 ERROR - Unresolved overloading *** Type : (RealFrac a, Integral a) => a *** Expression : getDecimal 1.23 I have tried adding "getDecimal :: Double -> Double" but it only causes the following message to appear: ERROR file:C:\Documents and Settings\User\file.hs:60 - Instance of Integral Double required for definition of getDecimal How should I define my function so that it'll work? Thanks! Regards, Dom
On Monday 23 November 2009 07:31:05 am Dominic Sim wrote:
I am trying to retrieve the decimal portion of a Double. My code is:
getDecimal x = x - floor(x)
The problem is that x is a double (or some other kind of floating point or fraction), and "floor x" is an integer, and you can't subtract an integer from a double. To convert "floor x" to a double (or to any other relevant type), use "fromIntegral", like: getDecimal x = x - fromIntegral(floor x) However, what I'd really suggest is that you use: getDecimal x = snd (properFraction x) or, in pointfree style: getDecimal = snd . properFraction Also, the type signature for getDecimal should be: getDecimal :: RealFrac a => a -> a That will allow it to be used with any Real or Fractional type. Shawn.
participants (2)
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Dominic Sim -
Shawn Willden