The app has a Transcript tab, where the result of the last line of the Playground tab's calculations or code is placed after pressing the "Run" button in Playground tab.

Commands to try:

1. 2+2
This puts 4 in the transcript tab.

2.
pi
prints value of pi

3. e
prints value of e

4.
global.f = x => x + 1
global.g = x => x * 2
global.h = compose(f, g);
h(3);
This prints 7 in the transcript tab(7 = 3*2 + 1)

5.
sum(range(0,100).map(random));
prints 100 random numbers.

The program behaves a lot like the JavaScript console in the browser.