Anagrams in Kotlin

Anagrams.kt

// we create a sequence that generates prime numbers
fun primes(): Sequence<Long> {
    var i = 2L
    return generateSequence { i++ }
            .filter { n -> (2L until n).none { n % it == 0L } }
}

// we map chars to a unique prime
val charToPrime = ('a'..'z').zip(primes().take(26).toList()).toMap()

// we transform a String to its prime product representation
fun String.toPrimeProduct() = this
        .filter { it != ' ' }
        .map { it.toLowerCase() }
        .fold(1L) { acc, c -> acc * charToPrime.getValue(c) }

// finally we simply say that two string are anagrams if their prime product is the same !
infix fun String.isAnagramOf(other: String) = this.toPrimeProduct() == other.toPrimeProduct()

// the infix function can be invoked !

"Clint Eastwood" isAnagramOf "Old West action" // true
"Madonna Louise Ciccone" isAnagramOf "One cool dance musician" // true
"This does not make sense" isAnagramOf "A wild red mongoose" // false