Can you list the main characteristics of hash functions?

The main characteristics of hash functions:

• Deterministic: for the same input, the hash function always returns the same hash.
• Fast computation: the hash should be computed quickly for any input.
• Distribution: hashes should be evenly distributed across the range to minimize collisions.
• Collision resistance: the probability that different inputs produce the same hash (collision) should be minimal.
• Pre-image resistance (for cryptographic hash functions): it should be infeasible to reconstruct the original data from the hash.

Example in Go:

import (
    "fmt"
    "hash/fnv"
)

func hash(s string) uint32 {
    h := fnv.New32a()
    h.Write([]byte(s))
    return h.Sum32()
}

func main() {
    fmt.Println(hash("example"))
}

Here, the FNV hash function is used for fast string hashing.