[plt-dev] strange behavior with printf, format, and unsyntax

This program:

#lang scheme

(display (format "~a~n" '(scheme #,3)))
(format "~a~n" '(scheme #,3))
(printf "~a~n" '(scheme #,3))

Produces these results:

(scheme (unsyntax 3))
"(scheme (unsyntax 3))\n"
(scheme #,3)

which rather surprised me.  Why is `printf' behaving differently from `format'?
-- 
sam th
samth at ccs.neu.edu