[R] I don't understand this
Thomas Lumley
tlumley at u.washington.edu
Wed Sep 3 15:56:26 CEST 2003
On Wed, 3 Sep 2003, Simon Fear wrote:
> Thanks to everyone for enlightening me about (f)(g). So I
> suppose (f)(g)(h)... is OK as long as (f)(g) returns a function with
> an argument (and so on)?
Indeed. As an example of what can be done
recurse <- function(f) {
g<- function(h)
function(x) f(h(h))(x)
g(g)
}
is not only syntactically valid, but arguably useful (it gives a way of
writing anonymous recursive functions), so that
recurse( function(self) function(n) if (n<2) 1 else n*self(n-1))
is an anonymous factorial function.
-thomas
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