const curry = fn => (...args) => args.length < fn.length
  ? (...rest) => curry(fn)(...args, ...rest)
  : fn(...args);

const applyTo = curry( (x, fn) => fn(x) );

const pipe = (headFN, ...restFns) => (...args) => restFns.reduce(applyTo, headFN(...args));
const prop = curry( (key, x) => x[key] );
const equals = curry( (x, y) => x === y );
const startsWith = curry( (str, x) => x.indexOf(str) === 0 );