[Haskell-cafe] Hierachical abstraction

Andrew Coppin andrewcoppin at btinternet.com
Fri Jan 29 13:47:54 EST 2010

Edward Kmett wrote:
> Luke pretty much nailed the summary of what you can parse using 
> Applicative means. I tend to consider them "codata CFGs", because they 
> can have infinite breadth and depth. However, a 'codata CFG' can 
> handle a much larger class of languages than CFGs.

Aren't CFGs banned in most countries due to concerns about the ozone layer?

> And yes, one of the major motivating ideas behind Arrows were the 
> parsers of Swierstra and Duponcheel 
> (http://citeseerx.ist.psu.edu/viewdoc/summary?doi=

Doesn't surprise me... ;-)

I'm not sure what such a parser would look like, but by the looks of it 
enough people have made them that I ought to be able to find some 
examples to look at if I search around.

(I must say, while the idea of arrows sounds nice, I've never actually 
tried using them due to the complexity of the mere syntax.)

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