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my first app in F#
f#functionaltutorial

Hello,

Couple of hours ago I decided to start learning some functional programming language and decided to choose F# because it is .NET-based and has integration with VS2005.

After reading quick tour I decided to write something and found a problem - it is hard to think out some good tutorial excersizes. After googling I found a link to article '15 Excersizes for Learning a new Programming Language'.

First task - Display series of numbers (1,2,3,4, 5....etc) in an infinite loop. The program should quit if someone hits a specific key (Say ESCAPE key) - completely discouraged me and after 1.5 hours of fighting with new syntax and teasing my brain I wrote the following code:

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let inc y:int = y + 1;;
let rec f x (y:int) = 
   if(System.Console.KeyAvailable && (System.Console.ReadKey().KeyChar = x))  then 
      System.Console.WriteLine("end")
   else begin
      System.Console.WriteLine(y);
      f x (inc y)
   end
;; 
f (Char.chr 27) 1;;

Could anyone comment it? Is there some more beatiful and natural solution?

Also, does anyone know where can I find more excersizes to learn thinking in functional paradigm?

.

What you have written is okay, but if I were doing it I'd have probably used some of the library function to replace some of the control flow you are using. Here is my effort:

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#light
// create infinte list of all integers
let ints = IEnumerable.init_infinite (fun x -> x)

// interate over the list of integers
ints
|> IEnumerable.iter 
    (fun x -> 
        if System.Console.KeyAvailable && System.Console.ReadKey().KeyChar = 'q' then
            exit 0
        System.Console.WriteLine(x))
By on 9/26/2006 8:17 AM ()

Since the training exercises are definitely in the world of imperative programming, its also OK just to use a while loop with a reference cell for the counter:

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#light

open System
let count = ref 0
while not (Console.KeyAvailable && (Console.ReadKey().Key = ConsoleKey.Escape))  do
    Console.WriteLine(!count);
    incr count
Console.WriteLine("end")

Don

By on 9/26/2006 10:43 PM ()

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