Two questions: a) This chat server implementation doesn't actually close the connection as a real one would need to do. If you use "forever" is there a way to end the loop so as to end the connection?
b) In Section 5 of this paper: http://www.cs.yale.edu/~hl293/download/leak.pdf Comparing the definition of eSF and e reveals that the primary difference is > in > the fixed-point operators they use. e uses Haskell’s built-in fixed-point > operator, > which is equivalent to the standard: > > fix f = f (fix f) > eSF, on the other hand, is defined in terms of the loop combinator, which > ties the loop > tighter than the standard fixed-point operator. In particular, note in > Figure 6 that > loop computes the value-level fixed point as z, but re-uses itself in the > continuation > part. This is the key to avoiding the space leak. > My reading is that the fix operator, at least in some cases, causes space leak. Where as the arrow's loop, which uses "let" model, doesn't have this issue. Question: Do I need to worry about space leak if I am using the fix to instead of the "let"? Thanks Daryoush 2009/3/5 Luke Palmer <lrpal...@gmail.com> > On Thu, Mar 5, 2009 at 6:27 PM, Donn Cave <d...@avvanta.com> wrote: > >> Quoth Jonathan Cast <jonathancc...@fastmail.fm>: >> >> > You can certainly use let: >> > >> > reader <- forkIO $ let loop = do >> > (nr', line) <- readChan chan' >> > when (nr /= nr') $ hPutStrLn hdl line >> > loop >> > in loop >> > >> > But the version with fix is clearer (at least to people who have fix in >> > their vocabulary) and arguably better style. >> >> Would you mind presenting the better style argument? To me, the >> above could not be clearer, so it seems like the version with fix >> could be only as clear, at best. > > > I like using fix when it's simple rather than let, because it tells me the > purpose of the binding. eg., when I see > > let foo = ... > > Where ... is fairly long, I'm not sure what the purpose of foo is, or what > its role is in the final computation. It may not be used at all, or passed > to some modifier function, or I don't know what. Whereas with: > > fix $ \foo -> ... > > I know that whatever ... is, it is what is returne, and the purpose of foo > is to use that return value in the expression itself. > > I know that it's a simple matter of scanning to the corresponding "in", but > let can be used for a lot of things, where as fix $ \foo is basically only > for simple knot-tying. Now, that doesn't say anything about the use of fix > without an argument (passed to an HOF) or with a tuple as an argument or > many other cases, which my brain has not chunked nearly as effectively. I > think fix is best with a single, named argument. > > Luke > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > >
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