Why does #s(foo :bar baz) cause error in ACL?

[sawada@etl.go.jp (Toshimi sawada)]

Would someone give me an answer, please?

Why, in Allegro CL, sharp sign macros for builtin atoms like
structure, array, etc. cause error?

	<etlclt:25> (defstruct foo bar)
	FOO 	
	<etlclt:26> (make-foo :bar 'baz)
	#s(FOO :BAR BAZ) 
	<etlclt:27> #s(FOO :BAR BAZ) 
	Error: #s(FOO :BAR BAZ) -- invalid form for eval.
	[1] <etlclt:28> :pop
	<etlclt:29> (make-array 2)
	#(NIL NIL) 
	<etlclt:30> #(nil nil)
	Error: #(NIL NIL) -- invalid form for eval.
	[1] <etlclt:31>

Thanks in advance.
--
T. Sawada         Electrotechnical Laboratory, Japan
sawada@etl.go.jp  Computer Language Section.