Problem Statement

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.

Let's start with the solution:

Integer method: isPrime
| i |
   self 1 <= ifTrue: [ false return ]
   self 3 <= ifTrue: [ true return ]
   self isEven ifTrue: [ false return ]
   3 self sqrt asInteger for: i [ self i mod ifzero: [ false return ] ]
   true ;