Reader syntax is what the R6RS report calls "lexical syntax" (section 4
of R6RS). Reader syntax is stuff that the `read` procedure handles. This
is stuff like vectors, strings, symbols, and lists. Reader syntax is
different from syntax like `(lambda (x) ...)` or `syntax-rules` (what
R6RS calls the "program syntax") because reader syntax is character based.

Some of the SRFIs add new reader syntax to Scheme, and the library
system in R6RS/R7RS has no way to import new reader syntax. However,
some of the SRFIs also add new procedures. SRFIs that add new procedures
should be given library names, because the new procedures should be
stored in a library.

For example, SRFI-4 adds #u8, #s16, #u32, etc. as reader syntax for
constant fixed-width vectors. It also adds u8vector-ref, s16vector-ref,
u32vector-ref, etc. as procedures. SRFI-261 should give SRFI-4 a library
name, because it has procedures that one could import, even if it reader
syntax modifications unspecified. That is because I should be able to
import `(srfi srfi-4)` or `(srfi numeric-vectors-4)` and get those
procedures.

On 7/3/25 02:01, WANG Zheng wrote:
> As for reader syntax, maybe you could give me some more information? I
> personally know some syntax within Chez Scheme's context and search
> engine (bing) can't directly explain it to me.