arithmetic-shift on negative number added by sethalves on Sat Jan 25 00:29:45 2014

ponk% chibi-scheme -e '(begin (import (scheme base) (scheme write) (srfi 33)) (display (arithmetic-shift -1 2)) (newline))'
4

ponk% csi -e '(begin (display (arithmetic-shift -1 2)) (newline))'                       
-4

sash> (bitwise-arithmetic-shift -1 2)
-4

gosh> (arithmetic-shift -1 2)
-4