Eugene Kirpichov wrote:
Most of the well-known algorithms are first-order, in the sense that their input and output are "plain" data. Some are second-order in a trivial way, for example sorting, hashtables or the map and fold functions: they are parameterized by a function, but they don't really do anything interesting with it except invoke it on pieces of other input data.
[...]
For example, parser combinators are not so interesting: they are a bunch of relatively orthogonal (by their purpose) combinators, each of which is by itself quite trivial, plus not-quite-higher-order backtracking at the core.
Aww, and there I thought that a famous function of 6th order for combining parsers would be to your liking: Chris Okasaki. Even Higher-Order Functions for Parsing or Why Would Anyone Ever Want To Use a Sixth-Order Function? http://www.eecs.usma.edu/webs/people/okasaki/jfp98.ps Regards, Heinrich Apfelmus -- http://apfelmus.nfshost.com