birthday.tiny

###############################################################
#
# The following program calculates the smallest number of people
# in a room for whom the probability of completely unique birthdays
# is less than 50% (the birthday problem, where for 1 person the
# probability is 365/365 (or 100%), for 2 it is 364/365, for 3
# it is 364/365 it is 363/365, etc.) (answer = 23).
#
# This example is adapted from the Ocaml example included in the
# Ocaml Wikipedia entry.
#
###############################################################

year_size = 365

fn birthday_paradox prob people {
    # use immediately-invoked lambda to avoid having
    # to reassign prob
    { prob -> 
        if (prob < 0.5) {
            println("answer = {0}\n", people+1)
        }
        else {
            warn("Recursing with people == {0}", people+1)
            birthday_paradox(prob, people+1)
        }
    } ((year_size - people) / year_size * prob)
}

birthday_paradox(1.0, 1)