Jason Kikel (4) [Avatar] Offline
#1
Using a hypothetical language might cause create more trouble than good. If the reader is not a functional programmer, an additional new syntax might turn out to confuse him or her more.

Maybe just provide the F# code and explain how it works.
let rec SumNumbers from to =
  if from > to then 0
  else
    let sumRest = SumNumbers(from + 1, to)
    from + sumRest


Or even, leave the hypothetical example in there and add the F# after it to complete the transition from C# style to F# style.
Jason Kikel (4) [Avatar] Offline
#2
Re: Section 2.2.2
Sorry about the weird formatting. Code brackets seem to be broken.
Tomas Petricek (160) [Avatar] Offline
#3
Re: Section 2.2.2
Hi,
this has also changed since the last update smilie. The new version shows how a simiar thing would look using standard C# switch and then using pattern matching in F# (after showing a declaration of the discriminated union).

Thanks
T.
davidmorton (1) [Avatar] Offline
#4
Re: Section 2.2.2
When I was looking over the "fictional language" it did occur to me that escaping C# isn't really necessary at all here.

static int SumNumbers(int x, int y)
{
return x > y ? 0 : x + SumNumbers(x + 1, y);
}

Is perfectly legal and compilable in C#, although I'd certainly agree with the switch to F#. F# uses a while loop to handle tail recursion and the example I posted above is very prone to a StackOverflowException.

Message was edited by:
davidmorton
Tomas Petricek (160) [Avatar] Offline
#5
Re: Section 2.2.2
Hi,
this is really difficult choice - I changed it back to standard C# and then back to pseudo-C# again. I didn't want to start with F#, because I wanted to make the chapter 2 as "light" as possible and the F# syntax could be difficult to read for some readers in the beginning.

Anyway, the reason why I ended up with pseudo C# is that I really want to be able to demonstrate how let-bindings (that are also expressions) work - the fact that you can write (using the pseudo-C#):

return x > y ? 0 : { var rest = SumNumbers(x+1, y) in x + rest };

T.