is-a-number-prime

Is a number prime?

• Completed at: 2023-02-11T06:23:04.087Z

• Completed languages: javascript, python

• Tags: Mathematics, Algorithms

• Rank: 6 kyu

Description

Define a function that takes an integer argument and returns a logical value true or false depending on if the integer is a prime.

Per Wikipedia, a prime number ( or a prime ) is a natural number greater than 1 that has no positive divisors other than 1 and itself.

Requirements

• You can assume you will be given an integer input.
• You can not assume that the integer will be only positive. You may be given negative numbers as well ( or 0 ).
• NOTE on performance: There are no fancy optimizations required, but still the most trivial solutions might time out. Numbers go up to 2^31 ( or similar, depending on language ). Looping all the way up to n, or n/2, will be too slow.

Example

is_prime(1)  /* false */
is_prime(2)  /* true  */
is_prime(-1) /* false */

mov edi, 1
call is_prime    ; EAX <- 0 (false)

mov edi, 2
call is_prime    ; EAX <- 1 (true)

mov edi, -1
call is_prime    ; EAX <- 0 (false)

bool isPrime(5) = return true

bool isPrime(5) = return true

IsPrime(1) = false
IsPrime(2) = true
IsPrime(-1) = false

is_prime(1)  # 0
is_prime(2)  # 1
is_prime(-1) # 0

is-prime 1 -> False
is-prime 2 -> True

## Encodings

purity: `LetRec`  
numEncoding: `BinaryScott` ( so, no negative numbers )  
export deconstructor `if` for your `Boolean` encoding