Thank you guys, i didn't understand the concept of the chapter.
Brent Yorgey wrote: > > On 7/25/07, Alexteslin <[EMAIL PROTECTED]> wrote: >> >> >> Hi, >> >> I am going through examples from the textbook and trying them out but >> some >> don't work. >> For example: >> >> addNum :: Int -> (Int -> Int) >> addNum n = addN >> where >> addN m = n+m >> >> This error message i am getting: >> >> ERROR - Cannot find "show" function for: >> *** Expression : addNum 4 >> *** Of type : Int -> Int > > > Hi, > > Printing functions is in general not possible, since given a function f > there is no way to "get at" its implementation.* Functions are like black > boxes. The only way to observe a function is to observe its effect on > various inputs. So you can try (addNum 4) 6, (addNum 4) 0, and so on to > see what the function (addNum 4) does to various Int values. > > cheers, > -Brent > > *(If there were it would lead to all sorts of fun > non-referential-transparency...) > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > > -- View this message in context: http://www.nabble.com/Printing-the-function-result-tf4145303.html#a11798690 Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe