[Haskell-cafe] Re: DDC compiler and effects; better than Haskell?

[roconnor at theorem.ca]

On Wed, 12 Aug 2009, Peter Verswyvelen wrote:

> I kind of agree with the DDC authors here; in Haskell as soon as a
> function has a side effect, and you want to pass that function to a
> pure higher order function, you're stuck, you need to pick the monadic
> version of the higher order function, if it exists. So Haskell doesn't
> really solve the modularity problem, you need two versions of each
> higher order function really,

Actually you need five versions: The pure version, the pre-order 
traversal, the post-order traversal, the in-order traversal, and the 
reverse in-order traversal.  And that is just looking at syntax.  If you 
care about your semantics you could potentially have more (or less).

-- 
Russell O'Connor                                      <http://r6.ca/>
``All talk about `theft,''' the general counsel of the American Graphophone
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