[Haskell-cafe] Theoretical question: are side effects necessary?

David Thomas davidleothomas at gmail.com
Fri Mar 16 23:38:47 CET 2012

If the question is "when can I have my output", then both are equally
relevant and can be safely conflated.

That said, while some programming problems *are* of this type, I think
most aren't, and your points certainly stand.

On Fri, Mar 16, 2012 at 3:31 PM, Chris Smith <cdsmith at gmail.com> wrote:
> On Fri, Mar 16, 2012 at 3:43 PM, serialhex <serialhex at gmail.com> wrote:
>> an interesting question emerges:  even though i may be able to implement an
>> algorithm with O(f(n)) in Haskell, and write a program that is O(g(n)) <
>> O(f(n)) in C++ or Java...  could Haskell be said to be more efficient if
>> time spent programming / maintaining Haskell is << C++ or Java??
> There are two unrelated issues: (a) the efficiency of algorithms
> implementable in Haskell, and (b) the efficiency of programmers
> working in Haskell.  It makes no sense to ask a question that
> conflates the two.  If you're unsure which definition of "efficient"
> you meant to ask about, then first you should stop to define the words
> you're using, and then ask a well-defined question.
> That being said, this question is even more moot given that real
> Haskell, which involves the IO and ST monads, is certainly no
> different from any other language in its optimal asymptotics.  Even if
> you discount IO and ST, lazy evaluation alone *may* recover optimal
> asymptotics in all cases... it's known that a pure *eager* language
> can add a log factor to the best case sometimes, but my understanding
> is that for all known examples where that happens, lazy evaluation
> (which can be seen as a controlled benign mutation) is enough to
> recover the optimal asymptotics.
> --
> Chris Smith
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