# Rosalind: IPRB — Mendel's First Law
# https://rosalind.info/problems/iprb/
#
# Given: Positive integers k (homozygous dominant), m (heterozygous) and
# n (homozygous recessive) organisms.
# Return: The probability that two randomly chosen mating organisms produce an
# individual with a dominant allele.

let k = 2.0
let m = 2.0
let n = 2.0
let total = k + m + n

# Work out the recessive probability and subtract: only mm, mn and nn pairings
# can produce a recessive offspring.
# A continued expression keeps its operator at the end of the line.
let mm = (m / total) * ((m - 1.0) / (total - 1.0)) * 0.25
let mn = (m / total) * (n / (total - 1.0)) * 0.5
let nm = (n / total) * (m / (total - 1.0)) * 0.5
let nn = (n / total) * ((n - 1.0) / (total - 1.0))
let p_recessive = mm + mn + nm + nn

let result = 1.0 - p_recessive

println("Result:   " + str(round(result, 5)))
println("Expected: 0.78333")

fn test_iprb_dominant_probability() {
    assert round(result, 5) == 0.78333, "IPRB: got " + str(result)
}