I can't comment on using ghci debugger to observe evaluation. I have in the past used hood (http://hackage.haskell.org/package/hood) and found it both convenient and useful when trying to observe evaluation order. On 2/11/2011 7:00 AM, Captain Freako wrote:
Hi John,
I'm trying to use the GHCI debugger on this code:
20 instance ArrowLoop SF where 21 loop (SF f) = SF $ \as -> 22 let (bs, cs) = unzip (f (zip as (stream cs))) in bs 23 where stream ~(x:xs) = x : stream xs 24 25 swap :: (a,b) -> (b,a) 26 swap (x,y) = (y,x)
in order to watch the recursion of the `loop' function unfold. However, when I single step through the code, I never stop on line 22 (where I could, presumably, peek in at `bs' and `cs', in order to see them develop):