/** This is a solver for the Rosetta Code problem
    "Safe primes and unsafe primes":

    https://rosettacode.org/wiki/Safe_primes_and_unsafe_primes
*/

safePrimes[end=undef] := select[primes[5,end], {|p| isPrime[(p-1)/2] }]
unsafePrimes[end=undef] := select[primes[2,end], {|p| p<5 or !isPrime[(p-1)/2] }]
println["First 35 safe primes:  " + first[safePrimes[], 35]]
println["Safe primes below  1,000,000: " + length[safePrimes[1_000_000]]]
println["Safe primes below 10,000,000: " + length[safePrimes[10_000_000]]]

println["First 40 unsafe primes:  " + first[unsafePrimes[], 40]]
println["Unsafe primes below  1,000,000: " + length[unsafePrimes[1_000_000]]]
println["Unsafe primes below 10,000,000: " + length[unsafePrimes[10_000_000]]]