constant target = "METHINKS IT IS LIKE A WEASEL",
         AZS    = "ABCDEFGHIJKLMNOPQRSTUVWXYZ ",
         C = 5000,  -- children in each generation
         P = 15     -- probability of mutation (1 in 15)

function fitness(string sample, string target)
    return sum(sq_eq(sample,target))
end function

function mutate(string s, integer n)
    for i=1 to length(s) do
        if rand(n)=1 then
            s[i] = AZS[rand(length(AZS))]
        end if
    end for
    return s
end function

string parent = mutate(target,1) -- (mutate with 100% probability)
sequence samples = repeat(0,C)
integer gen = 0, best, fit, best_fit = fitness(parent,target)
while parent!=target do
    printf(1,"Generation%3d: %s, fitness %3.2f%%\n", {gen, parent, (best_fit/length(target))*100})
    best_fit = -1
    for i=1 to C do
        samples[i] = mutate(parent, P)
        fit = fitness(samples[i], target)
        if fit > best_fit then
            best_fit = fit
            best = i
        end if
    end for
    parent = samples[best]
    gen += 1
end while
printf(1,"Finally, \"%s\"\n",{parent})