Do you mean Okasakis "Even higher-order functions for parsing or Why would
anyone ever want to use a sixth-order function?"?
2007/12/14, Ben Lippmeier
Hi all,
I'm working on a type-based side effect analysis for a Haskell-like language, and need to test it against some more higher order functions. The situation is a bit icky because it uses bounded quantification and various related issues (ie covariance vs contravariance) only come into play when dealing with functions of order >= 3.
Trouble is, the vast majority of useful higher order functions that I can think of are of order 2. Oh, I can certainly invent toys like:
order3 f = f succ order4 b f = if b then f else order3
.. and so on, but I'm left feeling unsatisfied.
I vaguely remember a paper called something like "Is there any use for a seventh order function?", but I forget why they were used, and I can't find it on Google, or ACM or any of the other likely places.
Does anyone have any examples of code (in whatever language) which usefully uses functions of order >= 3?? Preferably up to 5?
Thanks, Ben.
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