es.sh

#!/usr/bin/env bash

slugSha256() {
  slug=$(echo -n "$1" | sha256sum | cut -d' ' -f1)
  echo -n $((16#"${slug:0:8}"))
}

functionHash() {
  hash=$(slugSha256 "$(echo -n "$1" | sed 's/ //g')")
  if [[ "$1" == *constructor* ]] || [[ "$1" == *cell* ]] || [[ "$1" == *bytes* ]]; then
    hash=$((hash ^ (2 ** 31)))
  fi
  if [[ "$1" == *cell* ]]; then hash=$((hash ^ (2 ** 31))); fi
  if [[ "$1" == *bytes* ]]; then hash=$((hash ^ (2 ** 31))); fi
  printf '0x%x' "$hash"
}

functionID() { functionHash "$1v2"; }

functionID "$1"
echo

$ bash es.sh "main()(string)"
0xb0992770
$ bash es.sh "redeem(uint256, string, uint256)()"
0x58160fa0
$ bash es.sh "constructor()()"
0x68b55f3f

Also see

• es.ts
• es.js