Supercollider

{SinOsc.ar(440, 0, 0, 0)}.play;

• { .. }: a function
• SinOsc: Sinusoidal oscillator class
• .ar: Audio rate.
• .kr: Control rate.

{[SinOsc.ar(440, 0, 0, 0), SinOsc.ar(440, 0, 0, 0)]}.play;

• Playing an array does stereo (or more) output.