I\'m using chez-scheme and I can\'t find a way to clear the screen completely. (If someone knows a better way than printing I\'d be interested in that too but it\'s not my q
You can print \033c which resets the terminal:
\033c
petite -q <<< '(display "\033c")'
\033 is escape and c is literal c.
\033
c
I can't give you any information about how widely this is supported.