I propose to make a change,

	* srfi-1.c, srfi-1.h, srfi-1.scm (concatenate, concatenate!): Rewrite
	using scm_append and scm_append_x.

which should be smaller and faster.  I think it requires no more than
registering the following, since scm_append and scm_append_x don't
modify their list argument.

SCM_REGISTER_PROC (s_srfi1_concatenate,   "concatenate",  1, 0, 0, scm_append);
SCM_REGISTER_PROC (s_srfi1_concatenate_x, "concatenate!", 1, 0, 0, scm_append_x);