moy-fp/src/List/indexOf.js

A functional programming library.

import curry from '../Function/curry'
import equals from '../Relation/equals'

/**
 * a -> [a] -> Number
 */
const indexOf = curry(
  (predItem, list) => {
    const entries = list.entries()
    for(let [index, item] of entries){
      if(equals(predItem, item)){
        return index
      }
    }
    return -1
  }
)

export default indexOf