Task

Write a boolean function that tells whether a given integer is prime.



Remember that   1   and all non-positive numbers are not prime.

Use trial division.

Even numbers greater than   2   may be eliminated right away.

A loop from   3   to   √ n    will suffice,   but other loops are allowed.



Related tasks

   count in factors
   prime decomposition
   AKS test for primes
   factors of an integer
   Sieve of Eratosthenes
   factors of a Mersenne number
   trial factoring of a Mersenne number
   partition an integer X into N primes
   sequence of primes by Trial Division


| isPrime |
isPrime := [:n |
    n even ifTrue: [ ^n=2 ]
    ifFalse: [
        3 to: n sqrt do: [:i |
            (n \\ i = 0) ifTrue: [ ^false ]
        ].
        ^true
    ]
]