Andrew Stanton and Jim Reardon

WALL-E is practically silent for the first thirty minutes, aside from robo bleeps and bloops, a few lasers and explosions, and the skittering of the friendliest cockroach on Earth. That must have been an easy screenplay to write, huh?

Not so fast. Stanton and Reardon not only studied the silent films of Charlie Chaplin and Buster Keaton, but they wrote the script in an abbreviated

Shorthand style
With just a few words
On each line, so it
Kind of looked like a haiku.

They also wrote what they intended each character to say, as if they could speak, and they could go back and fill in specific technological sound effects depending on the type of robot (source).