warumvogel/01drossel.R

# Drossel: fn => fn(fn)
# usage: drossel(function(self, arg1, arg2))
# it's basically just a factory hiding the function name
# in a closure. easy!
drossel <- function (func) function (...)  func(func, ...)

# example: factorial
# TODO: play with lazy evaluation?
fac_ <- function (self, n) {
  if (n < 2) 1
  else n * self(self, n - 1)
}

fac <- drossel(fac_)
  
fac(8)