Re: [Haskell-cafe] type Rational and the % operator

Just use "/" for division. % is for construction of rationals from the "underlying" numeric type. For example, instead of "toRational x" you can write "x % 1". -- ryan 2009/3/28 michael rice :

I may be missing something here, but this is what I intended.

An expression of the form

        1 a1 + ------             1     a2 + ------                  1          a3 + --                  a4 + ...

Where the ai's are positive integers is called a continued fraction.

Function cf should take [1,2,6,5] to produce

        1   1 + -----           1     2 + -----               1         6 + --               5

Michael

--- On Sat, 3/28/09, Brandon S. Allbery KF8NH wrote:

From: Brandon S. Allbery KF8NH Subject: Re: [Haskell-cafe] type Rational and the % operator To: "michael rice" Cc: "Brandon S. Allbery KF8NH" , "Duane Johnson" , haskell-cafe@haskell.org Date: Saturday, March 28, 2009, 10:39 PM

On 2009 Mar 28, at 22:36, michael rice wrote:

import Data.Ratio cf :: [Integer] -> Rational cf (x:xs) = (toRational x) + (1 % (cf xs)) cf (x:[]) = toRational x cf [] = toRational 0

Data.Ratio> :load cf.hs ERROR "cf.hs":3 - Type error in application *** Expression     : toRational x + 1 % cf xs *** Term           : toRational x *** Type           : Ratio Integer *** Does not match : Ratio (Ratio Integer)

Your function cf produces a Rational (Ratio Int); you're using it in the denominator of another Ratio, which makes that Ratio's type Ratio (Ratio Int).  This is almost certainly not what you intended, but I couldn't say what you actually want. -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allbery@kf8nh.com system administrator [openafs,heimdal,too many hats] allbery@ece.cmu.edu electrical and computer engineering, carnegie mellon university    KF8NH

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