deepFilter function uses the predicate to filter properties which may be nested deeply in the given value (object or array). It returns filtered object or array.

I attempted to use as much FP principles as I could think of and will appreciate any comments on things I did right and wrong (from FP perspective) and suggestions to improve.

const and = (f1, f2) => v => f1(v) && f2(v);  const or = (f1, f2) => v => f1(v) || f2(v);  const isArray = v => Array.isArray(v);  const isObject = v => typeof v === 'object' && v !== null;  const hasProps = v => Object.keys(v).length > 0;  const selector = (predicate, v1, v2) => v => (predicate(v) ? v1 : v2);  const isObjectOrArray = or(isArray, isObject);  const hasValue = and(isObjectOrArray, hasProps);  const initial = selector(isArray, [], {});  function deepFilter(value, predicate) {   if (isObjectOrArray(value)) {     return Object.keys(value).reduce((filtered, key) => {       if (predicate(key)) {         return { ...filtered, [key]: value[key] };       }       const v = deepFilter(value[key], predicate);       return hasValue(v) ? { ...filtered, [key]: v } : filtered;     }, initial());   }   return value; }