[Haskell-beginners] Global variable question
Joe Van Dyk
joe at fixieconsulting.com
Thu Dec 31 18:43:33 EST 2009
On Thu, Dec 31, 2009 at 3:38 PM, John Velman <velman at cox.net> wrote:
> On Thu, Dec 31, 2009 at 09:37:10AM -0800, Joe Van Dyk wrote:
>> On Wed, Dec 30, 2009 at 6:05 PM, Edward Z. Yang <ezyang at mit.edu> wrote:
>> > Excerpts from Joe Van Dyk's message of Wed Dec 30 20:49:12 -0500 2009:
>> >> What's the appropriate way to write this in Haskell?
>> > Hi Joe,
>> > The Ticker class is an example of stateful computation, which we try
>> > to avoid in Haskell. What are you really trying to do?
>> > * If you a number, and you want to add to it, (+1) works
>> > plenty well.
>> > * If you are going to be making ticks, but you don't care about
>> > reading the ticks until the end of the computation, the Writer monad
>> > is of interest.
>> > * If you need to update the tick count and read it, the State
>> > monad is a good bet.
>> > * If you're interested in curiosities from imperative land, STRef, IORef and
>> > other similar creatures may be helpful.
>> It's like haskell is on a personal vendetta against me to make me feel dumb.
> It's not personal.
Feels like it though. :(
More information about the Beginners