deeqSeq proposal

[Andy Gill]

On Apr 5, 2006, at 4:51 PM, John Meacham wrote:

> On Wed, Apr 05, 2006 at 10:34:09AM -0500, Spencer Janssen wrote:
>> How about an implementation that sets the deepSeq'd bit *after* each
>> field has been successfully deepSeq'd?  deepSeq'ing a cyclic  
>> structure
>> would behave just like an infinite structure.
>
> what would be the point of having a bit then?

Because deepSeq's cost to evaluate a list that will eventually be  
required is linear.
The maximum number of deepSeq calls (and recursive calls) you can do  
over any
structure is simply the number of nodes.

Consider:

   foldr (\ a as -> deepSeq (a : as)) [] $ some list

With the bit ==> one deepSeq per cons, then we hit the 'is-pre- 
deepSeqd' bit.
Without the bit ==> O(n^2)

> in any case, we should talk about the meaning of deepseqing something,
> not its implementation.
>
> depth limited recursive seq seems like the best route to me.
>
>         John
>
> -- 
> John Meacham - ⑆repetae.net⑆john⑈
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