Ok but whe the Thompson's book says: -------------------------------------------- Literals are not overloaded, there is no automatic conversion from Int to Float. .. we will receive an error message if we type
(floor 5.6) + 6.7 since we are trying to add quantities of two different types. We have to convert the Int to a Float to perform the addtion, thus: fromIntegral (floor 5.6) + 6.7 where fromInt takes int to corresponding Float. -------------------------------------------- pag. 45 "The Craft of Functional Programming" second edition sadly, if I use a integer number it's work! 5 + 6.7 WHY????? 5 is don't Integer like (floor 5.6)? -- Alfredo Paz-Valderrama Sociedad Peruana de Computacion Mensaje citado por Scott Turner <[EMAIL PROTECTED]>: > On 2005 April 12 Tuesday 23:12, Alfredo Paz-Valderrama wrote: > > If i write this in hugs: > > > > 1 / 2 > > > > I get 0.5 by answer, but the / operator signature is: > > > > float -> float -> float > > 1 and 2 are overloaded. They can be Integer, Float, etc. > > You can think of 2 as meaning (fromInteger 2). FromInteger is defined in the > Prelude to convert an Integer to any numeric type. > > Haskell organizes overloading using type classes. The type class called Num > contains fromInteger, +, -, and *. So these operators along with the integer > literals 1,2, etc. can be used with any numeric type. You can define your own > numeric type (for example polynomials) and use 1,2, and + with that. > > Actually, the / operator is not limited to Float, either. It is overloaded > for > the type class "Fractional", which includes Double and Rational. Hugs will > tell you the type is > Float -> Float -> Float > because there's a defaulting mechanism so that if multiple types are > possible, > Hugs can choose one and give you an answer. > ---------------------------------------------------------------- This mail sent through StarMail: http://www.star.com.pe _______________________________________________ Hugs-Users mailing list Hugs-Users@haskell.org http://www.haskell.org/mailman/listinfo/hugs-users