[Haskell-cafe] Re: evaluate vs seq

Lennart Augustsson lennart at augustsson.net
Fri Sep 15 07:59:57 EDT 2006

No, I wasn't suggesting that evaluate can tell the difference, just  
that you can add dubious "functions".

You can evaluate with eager evaluation and some kind of threads+fair  
scheduler.  Both pH and the (short lived) Eager Haskell version of  
ghc did this.  (Well, I'm not sure pH ever got the fair scheduler.)

	-- Lennart

On Sep 15, 2006, at 05:00 , apfelmus at quantentunnel.de wrote:

> Lennart Augustsson wrote:
>> No, you were right the first time. :)  The denotational semantics  
>> is the
>> important one.  Haskell can be executed by other means than graph
>> reduction.  (That's why the report says a "non-strict" rather than
>> "lazy" language.)  Peculiar language constructs may allow you to tell
>> the difference, but then they are highly dubious (and like all  
>> dubious
>> things, they should be in the IO monad :) ).
> You suggest that (evaluate) or something else actually can tell me the
> difference? That would be interesting.
> And what alternatives (besides call by name without sharing) are  
> there?
> I always think lazy evaluation is space and time optimal.
> Regards,
> apfelmus
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