var foo = R.set(R.lensProp('bar'), 'foo' + R.prop('foo'));
var result = foo({foo:"bar"});

{foo:"bar", bar:"foobar"}

{foo:"bar", bar: "foofunction f1(a) {... etc"}

const foo = o => R.assoc('bar', 'foo' + o.foo, o);

foo({foo: 'bar'});
// => {foo: 'bar', bar: 'foobar'}

var foo = (obj) => R.assoc('bar', 'foo' + obj.foo, obj);
var foo = R.converge(R.assoc('bar'), [R.pipe(R.prop('foo'), R.concat('foo')), R.identity]);

import { curry, assoc, compose, evolve } from 'ramda'

// String -> String -> {k: v}
const copyPropAs = curry((from, to, obj) => assoc(to, obj[from], obj))

// String -> String -> String
const prefix = curry((value, string) => value + string)

const fn = compose(
  evolve({
    foo: prefix('foo')
  }),
  copyPropAs('foo', 'bar')
)

fn({foo: 'bar'})